Method and apparatus for controlling uplink control information in wireless communication system

ABSTRACT

Provided is a method and an apparatus for transmitting uplink control information by a terminal in wireless communication system. When a PUCCH resource used for transmitting only periodic CSI from a subframe, the resource is a first resource, and a resource indicated by ARI is a second resource, when a setting allows transmitting together ACK/NACK and the periodic CSI through a PUCCH from the same subframe, the first resource and the second resource are mutually exclusive, and the second resource that is used for transmitting together the ACK/NACK and the periodic CSI uses the resource indicated by the ARI from resources determined by an RRC.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to wireless communications, and moreparticularly, to a method and apparatus for transmitting uplink controlinformation in a wireless communication system.

Related Art

In order to maximize efficiency of limited radio resources, an effectivetransmission and reception scheme and methods of utilization thereofhave been proposed in a broadband wireless communication system. Anorthogonal frequency division multiplexing (OFDM) system capable ofreducing inter-symbol interference (ISI) with a low complexity is takeninto consideration as one of next generation wireless communicationsystems. In the OFDM, a serially input data symbol is converted into Nparallel data symbols, and is then transmitted by being carried on eachof separated N subcarriers. The subcarriers maintain orthogonality in afrequency dimension. Each orthogonal channel experiences mutuallyindependent frequency selective fading. As a result, complexity isdecreased in a receiving end and an interval of a transmitted symbol isincreased, thereby minimizing the ISI.

In a system using the OFDM as a modulation scheme, orthogonal frequencydivision multiple access (OFDMA) is a multiple access scheme in whichmultiple access is achieved by independently providing a part ofavailable subcarrier to each user. In the OFDMA, frequency resources(i.e., subcarriers) are provided to respective users, and the respectivefrequency resources do not overlap with one another in general sincethey are independently provided to the multiple users. Consequently, thefrequency resources are allocated to the respective users in a mutuallyexclusive manner. In an OFDMA system, frequency diversity for themultiple users can be obtained by using frequency selective scheduling,and subcarriers can be allocated variously according to a permutationrule for the subcarriers. In addition, a spatial multiplexing schemeusing multiple antennas can be used to increase efficiency of a spatialdomain.

A multiple input multiple output (MIMO) technique uses multiple transmitantennas and multiple receive antennas to improve datatransmission/reception efficiency. Exemplary methods for implementingdiversity in a MIMO system include space frequency block code (SFBC),space time block code (STBC), cyclic delay diversity (CDD), frequencyswitched transmit diversity (FSTD), time switched transmit diversity(TSTD), precoding vector switching (PVS), spatial multiplexing (SM),etc. A MIMO channel matrix depending on the number of receive antennasand the number of transmit antennas can be decomposed into a pluralityof independent channels. Each independent channel is referred to as alayer or a stream. The number of layers is referred to as a rank.

Uplink control information (UCI) can be transmitted through a physicaluplink control channel (PUCCH). The UCI can include various types ofinformation such as a scheduling request (SR), anacknowledgement/non-acknowledgement (ACK/NACK) signal for hybridautomatic repeat request (HARQ), a channel quality indicator (CQI), aprecoding matrix indicator (PMI), a rank indicator (RI), etc. The PUCCHcarries various types of control information according to a format.

A carrier aggregation system has recently drawn attention. The carrieraggregation system implies a system that configures a broadband byaggregating one or more carriers having a bandwidth smaller than that ofa target broadband when the wireless communication system intends tosupport the broadband.

There is a need for a method for effectively and reliably transmittingvarious types of UCI in the carrier aggregation system.

SUMMARY OF THE INVENTION

The present invention proposes a method and apparatus for transmittinguplink control information in a wireless communication system.

According to an aspect of the present invention, a method oftransmitting uplink control information (UCI), performed by a terminalin a wireless communication system, is provided. The method includes:receiving a data unit requesting an acknowledgement/not-acknowledgement(ACK/NACK) response in a downlink subframe; and transmitting ACK/NACKfor the data unit in an uplink subframe, wherein if the uplink subframeis configured to transmit periodic channel state information (CSI), theperiodic CSI and the ACK/NACK are transmitted together through aphysical uplink control channel (PUCCH) of the uplink subframe, andwherein if an ACK/NACK resource indicator (ARI) is included in thedownlink subframe, a resource for transmitting the PUCCH is one resourceindicated by the ARI among a plurality of resources pre-assigned by ahigher layer signal.

In the aforementioned aspect of the present invention, uplink subframesin which the periodic CSI can be transmitted may be predetermined by ahigher layer signal.

In addition, a PUCCH format in which the ACK/NACK is transmitted may bepredetermined to one of a plurality of PUCCH formats by a higher layersignal.

In addition, the predetermined one PUCCH format may be a PUCCH formatcapable of transmitting an information bit of up to 22 bits.

In addition, if a PUCCH resource used when only periodic CSI istransmitted in the uplink subframe is a first resource, and if oneresource indicated by the ARI is a second resource, the first resourceand the second resource may be distinguished in a mutually exclusivemanner.

In addition, the ARI may be included in downlink control information(DCI) transmitted through a physical downlink control channel (PDCCH) ofthe downlink subframe.

In addition, the ACK/NACK and the periodic CSI may be joint-coded.

In addition, a data unit requesting the ACK/NACK response may be acodeword transmitted through a physical downlink shared channel (PDSCH)of the downlink subframe or a PDCCH transmitted in the downlinksubframe, and the PDCCH may be a PDCCH indicating a release ofsemi-persistent scheduling (SPS).

According to another aspect of the present invention, an apparatus fortransmitting uplink control information is provided. The apparatusincludes: a radio frequency (RF) unit for transmitting or receiving aradio signal; and a processor operatively coupled to the RF unit,wherein the processor is configured for: receiving a data unitrequesting an acknowledgement/not-acknowledgement (ACK/NACK) response ina downlink subframe; and transmitting ACK/NACK for the data unit in anuplink subframe, wherein if the uplink subframe is configured totransmit periodic channel state information (CSI), the periodic CSI andthe ACK/NACK are transmitted together through a physical uplink controlchannel (PUCCH) of the uplink subframe, and wherein if an ACK/NACKresource indicator (ARI) is included in the downlink subframe, aresource for transmitting the PUCCH is one resource indicated by the ARIamong a plurality of resources pre-assigned by a higher layer signal.

When there is a need to transmit different types of uplink controlinformation (UCI) in the same subframe, it can be effectivelymultiplexed and transmitted.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a structure of a radio frame in 3^(rd) generationpartnership project (3GPP) long term evolution (LTE).

FIG. 2 shows an example of a resource grid for one downlink (DL) slot.

FIG. 3 shows a structure of a DL subframe.

FIG. 4 shows a structure of an uplink (UL) subframe.

FIG. 5 shows an example of comparing a single-carrier system and acarrier aggregation system.

FIG. 6 shows a channel structure of physical uplink control channel(PUCCH) formats 2/2a/2b for one slot in a normal cyclic prefix (CP)case.

FIG. 7 shows a PUCCH format 1a/1b for one slot in a normal CP case.

FIG. 8 shows an example of constellation mapping ofacknowledgement/non-acknowledgement (ACK/NACK) in a normal CP case and aPUCCH format 2a/2b.

FIG. 9 shows an example of joint coding between ACK/NACK and channelquality indicator (CQI) in an extended CP case.

FIG. 10 shows a method of multiplexing ACK/NACK and scheduling request(SR).

FIG. 11 shows constellation mapping when ACK/NACK and SR aresimultaneously transmitted.

FIG. 12 shows an example of mapping channel-coded bits to acode-time-frequency resource.

FIG. 13 shows an example of a channel structure of a PUCCH format 3.

FIG. 14 shows an example of a dual Reed Muller (RM) coding process.

FIG. 15 shows an example of a method of segmenting a uplink controlinformation (UCI) bit stream.

FIG. 16 shows a channel coding method using double RM according to anembodiment of the present invention.

FIG. 17 shows an interleaver of FIG. 16 in detail.

FIG. 18 is a flowchart of a method described with reference to FIG. 16and FIG. 17.

FIG. 19 shows an example of a resource arrangement when ACK/NACK and CSIare transmitted through multiplexing.

FIG. 20 is an example of a 1^(st) resource and a 2^(nd) resource.

FIG. 21 shows an example of a resource selection method when ACK/NACKand CSI can be transmitted through multiplexing by using the sameformat.

FIG. 22 shows an example of a UCI configuration in a 1^(st) resource anda 2^(nd) resource.

FIG. 23 is an example of individual coding of ACK/NACK and CSI.

FIG. 24 is an example of a coding scheme of UCI.

FIG. 25 shows an example of including a UCI content indicator.

FIG. 26 is a block diagram of a base station and a user equipmentaccording to an embodiment of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The technology described below can be used in various wirelesscommunication systems such as code division multiple access (CDMA),frequency division multiple access (FDMA), time division multiple access(TDMA), orthogonal frequency division multiple access (OFDMA), singlecarrier frequency division multiple access (SC-FDMA), etc. The CDMA canbe implemented with a radio technology such as universal terrestrialradio access (UTRA) or CDMA2000. The TDMA can be implemented with aradio technology such as global system for mobile communications(GSM)/general packet ratio service (GPRS)/enhanced data rate for GSMevolution (EDGE). The OFDMA can be implemented with a radio technologysuch as institute of electrical and electronics engineers (IEEE) 802.11(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, evolved UTRA (E-UTRA), etc.IEEE 802.16m is evolved from IEEE 802.16e, and provides backwardcompatibility with an IEEE 802.16e-based system. The UTRA is a part of auniversal mobile telecommunication system (UMTS). 3^(rd) generationpartnership project (3GPP) long term evolution (LTE) is a part of anevolved UMTS (E-UMTS) using the E-UTRA. The 3GPP LTE uses the OFDMA in adownlink and uses the SC-FDMA in an uplink. LTE-advanced (LTE-A) isevolved from the 3GPP LTE. Although the following description focuses onLTE/LTE-A for clarity, the technical features of the present inventionare not limited thereto.

A wireless communication system includes at least one base station (BS).Each BS provides a communication service to a specific geographicalregion. A user equipment (UE) may be fixed or mobile, and may bereferred to as another terminology, such as a mobile station (MS), auser terminal (UT), a subscriber station (SS), a wireless device, apersonal digital assistant (PDA), a wireless modem, a handheld device,etc. The BS is generally a fixed station that communicates with the UEand may be referred to as another terminology, such as an evolved Node-B(eNB), a base transceiver system (BTS), an access point, etc.

The UE belongs to one cell in general. A cell to which the UE belongs iscalled a serving cell. A BS which provides a communication service tothe serving cell is called a serving BS. The serving BS may provide oneor a plurality of serving cells.

This technique can be used in a downlink or an uplink. In general, thedownlink implies communication from the BS to the UE, and the uplinkimplies communication from the UE to the BS.

Layers of a radio interface protocol between the UE and the BS can beclassified into a first layer (L1), a second layer (L2), and a thirdlayer (L3) based on the lower three layers of the open systeminterconnection (OSI) model that is well-known in the communicationsystem.

A physical layer, i.e., the first layer, is connected to a medium accesscontrol (MAC) layer, i.e., a higher layer, through a transport channel.Data between the MAC and physical layers is transferred through thetransport channel. Further, between different physical layers, i.e.,between a physical layer of a transmitting side and a physical layer ofa receiving side, data is transferred through a physical channel.

A radio data link layer, i.e., the second layer, consists of a MAClayer, an RLC layer, and a PDCP layer. The MAC layer is a layer thatmanages mapping between a logical channel and the transport channel. TheMAC layer selects a proper transport channel to transmit data deliveredfrom the RLC layer, and adds essential control information to a headerof a MAC protocol data unit (PDU).

The RLC layer is located above the MAC layer and supports reliable datatransmission. In addition, the RLC layer segments and concatenates RLCservice data units (SDUs) delivered from an upper layer to configuredata having a suitable size for a radio section. The RLC layer of areceiver supports a reassemble function of data to restore an originalRLC SDU from the received RLC PDUs.

The PDCP layer is used only in a packet exchange area, and can performtransmission by compressing a header of an IP packet to increasetransmission efficiency of packet data in a radio channel.

The RRC layer, i.e., the third layer, exchanges radio resource controlinformation between the UE and the network in addition to controlling ofa lower layer. According to a communication state of the UE, various RRCstates (e.g., an idle mode, an RRC connected mode, etc.) are defined,and transition between the RRC states is optionally possible. In the RRClayer, various procedures related to radio resource management aredefined such as system information broadcasting, an RRC accessmanagement procedure, a multiple component carrier setup procedure, aradio bearer control procedure, a security procedure, a measurementprocedure, a mobility management procedure (handover), etc.

The wireless communication system may be any one of a multiple-inputmultiple-output (MIMO) system, a multiple-input single-output (MISO)system, a single-input single-output (SISO) system, or a single-inputmultiple-output (SIMO) system. The MIMO system uses a plurality oftransmit antennas and a plurality of receive antennas. The MISO systemuses a plurality of transmit antennas and one receive antenna. The SISOsystem uses one transmit antenna and one receive antenna. The SIMOsystem uses one transmit antenna and a plurality of receive antennas.Hereinafter, a transmit (Tx) antenna implies a physical or logicalantenna used to transmit one signal or stream, and a receive (Rx)antenna implies a physical or logical antenna used to receive one signalor stream.

FIG. 1 shows a structure of a radio frame in 3GPP LTE.

The section 5 of 3GPP(3rd Generation Partnership Project) TS 36.211V8.2.0 (2008-03) “Technical Specification Group Radio Access Network;Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channelsand modulation (Release 8)” can be incorporated herein by reference.Referring to FIG. 1, the radio frame consists of 10 subframes. Onesubframe consists of two slots. Slots included in the radio frame arenumbered with slot numbers #0 to #19. A time required to transmit onesubframe is defined as a transmission time interval (TTI). The TTI maybe a scheduling unit for data transmission. For example, one radio framemay have a length of 10 milliseconds (ms), one subframe may have alength of 1 ms, and one slot may have a length of 0.5 ms.

One slot includes a plurality of orthogonal frequency divisionmultiplexing (OFDM) symbols in a time domain, and includes a pluralityof subcarriers in a frequency domain. Since the 3GPP LTE uses OFDMA indownlink transmission, the OFDM symbol is for representing one symbolperiod, and can be referred to as other terms. For example, the OFDMsymbol can also be referred to as an SC-FDMA symbol when SC-FDMA is usedas an uplink multiple-access scheme. A resource block (RB) is a resourceallocation unit, and includes a plurality of consecutive subcarriers inone slot. The above radio frame structure is shown for exemplarypurposes only. Thus, the number of subframes included in the radioframe, the number of slots included in the subframe, or the number ofOFDM symbols included in the slot may change variously.

In 3GPP LTE, it is defined such that one slot includes 7 OFDM symbols ina normal cyclic prefix (CP) and one slot includes 6 OFDM symbols in anextended CP.

A wireless communication system can be briefly classified into a systembased on a frequency division duplex (FDD) scheme and a system based ona time division duplex (TDD) scheme. In the FDD scheme, uplinktransmission and downlink transmission are achieved while occupyingdifferent frequency bands. In the TDD scheme, uplink transmission anddownlink transmission are achieved at different times while occupyingthe same frequency band. A channel response based on the TDD scheme isreciprocal in practice. This implies that a downlink channel response isalmost identical to an uplink channel response in a given frequencydomain. Therefore, in a TDD-based wireless communication system, thedownlink channel response can be advantageously obtained from the uplinkchannel response. In the TDD scheme, a full frequency band istime-divided into UL transmission and DL transmission, and thus DLtransmission performed by a BS and UL transmission performed by a UE canbe simultaneously achieved. In a TDD system in which UL transmission andDL transmission are divided on a subframe basis, UL transmission and DLtransmission are performed in different subframes.

FIG. 2 shows an example of a resource grid for one DL slot.

The DL slot includes a plurality of OFDM symbols in a time domain, andincludes N_(RB) resource blocks (RBs) in a frequency domain. The numberN_(RB) of RBs included in the DL slot depends on a DL transmissionbandwidth configured in a cell. For example, in the LTE system, N_(RB)may be any one value in the range of 6 to 110. One RB includes aplurality of subcarriers in a frequency domain. A structure of a UL slotmay be the same as the aforementioned structure of the DL slot.

Each element on the resource grid is referred to as a resource element(RE). The RE on the resource grid can be identified by an index pair(k,l) within the slot. Herein, k(k=0, . . . ,N_(RB)×12−1) denotes asubcarrier index in the frequency domain, and l(l=0, . . . ,6) denotesan OFDM symbol index in the time domain.

Although it is described herein that one RB consists of 7 OFDM symbolsin the time domain and 12 subcarriers in the frequency domain and thusincludes 7×12 REs, this is for exemplary purposes only. Therefore, thenumber of OFDM symbols and the number of subcarriers in the RB are notlimited thereto. The number of OFDM symbols and the number ofsubcarriers may change variously depending on a CP length, a frequencyspacing, etc. For example, the number of OFDM symbols is 7 in a normalCP case, and the number of OFDM symbols is 6 in an extended CP case. Thenumber of subcarriers in one OFDM symbol may be selected from 128, 256,512, 1024, 1536, and 2048.

FIG. 3 shows a structure of a downlink subframe.

The downlink subframe includes two slots in a time domain. Each slotincludes 7 OFDM symbols in a normal CP case. Up to three OFDM symbols(i.e., in case of 1.4 MHz bandwidth, up to 4 OFDM symbols) located in afront portion of a first slot within the subframe correspond to acontrol region, and the remaining OFDM symbols correspond to a dataregion. Herein, control channels are allocated to the control region,and a physical downlink shared channel (PDSCH) is allocated to the dataregion.

A physical downlink control channel (PDCCH) can carry a downlink sharedchannel (DL-SCH)'s resource allocation (referred to as a downlink (DL)grant) and transmission format, uplink shared channel (UL-SCH)'sresource allocation information (referred to as an uplink (UL) grant),paging information on a PCH, system information on a DL-SCH, a resourceallocation of a higher layer control message such as a random accessresponse transmitted through a PDSCH, a transmission power controlcommand for individual UEs included in any UE group, activation of avoice over Internet (VoIP), etc. A plurality of PDCCHs can betransmitted in the control region, and the UE can monitor the pluralityof PDCCHs. The PDCCH is transmitted on an aggregation of one or severalconsecutive control channel elements (CCEs). The CCE is a logicalallocation unit used to provide the PDCCH with a coding rate based on astate of a radio channel. The CCE corresponds to a plurality of resourceelement groups (REGs). A format of the PDCCH and the number of bits ofthe available PDCCH are determined according to a correlation betweenthe number of CCEs and the coding rate provided by the CCEs.

A BS determines a PDCCH format according to DCI to be transmitted to aUE, and attaches a cyclic redundancy check (CRC) to control information.The CRC is masked with a unique identifier (referred to as a radionetwork temporary identifier (RNTI)) according to an owner or usage ofthe PDCCH. If the PDCCH is for a specific UE, a unique identifier (e.g.,cell-RNTI (C-RNTI)) of the UE may be masked to the CRC. Alternatively,if the PDCCH is for a paging message, a paging indicator identifier(e.g., paging-RNTI (P-RNTI)) may be masked to the CRC. If the PDCCH isfor a system information block (SIB), a system information identifierand a system information RNTI (SI-RNTI) may be masked to the CRC. Toindicate a random access response that is a response for transmission ofa random access preamble of the UE, a random access-RNTI (RA-RNTI) maybe masked to the CRC.

FIG. 4 shows a structure of an uplink subframe.

The uplink subframe can be divided into a control region and a dataregion. A physical uplink control channel (PUCCH) for carrying uplinkcontrol information (UCI) is allocated to the control region. A physicaluplink shared channel (PUSCH) for carrying uplink data is allocated tothe data region.

When indicated by a higher layer, a UE may support simultaneoustransmission of the PUSCH and the PUCCH.

The PUCCH for one UE is allocated in an RB pair in a subframe. RBsbelonging to the RB pair occupy different subcarriers in each of a1^(st) slot and a 2^(nd) slot. That is, a frequency occupied by the RBsbelonging to the RB pair to which the PUCCH is allocated changes at aslot boundary. This is called that the RB pair allocated to the PUCCH isfrequency-hopped at the slot boundary. Since the UE transmits the UCI ona time basis through different subcarriers, a frequency diversity gaincan be obtained.

The PUSCH is a channel mapped to a UL-SCH (uplink shared channel) whichis a transport channel. Uplink data transmitted through the PUSCH may bea transport block which is a data block for the UL-SCH transmittedduring a TTI. The transport block may include user information. Inaddition, the uplink data may be multiplexed data. The multiplexed datamay be obtained by multiplexing control information and a transportblock for the UL-SCH. Examples of the control information multiplexed tothe data may include CQI, PMI (precoding matrix indicator), HARQACK/NACK, RI (rank indicator), etc. Alternatively, the uplink data mayconsist of only the control information.

Meanwhile, a wireless communication system may be a carrier aggregationsystem. Herein, carrier aggregation is when a broadband is configured byaggregating one or more carriers having a smaller bandwidth than thebroadband. The carrier aggregation system can configure a broadband byaggregating one or more component carriers (CCs) having a bandwidthsmaller than that of a target broadband when the wireless communicationsystem intends to support the broadband.

FIG. 5 shows an example of comparing a single-carrier system and acarrier aggregation system.

Referring to FIG. 5, only one carrier is supported for a UE in an uplinkand a downlink in the single-carrier system. Although the carrier mayhave various bandwidths, only one carrier is assigned to the UE.Meanwhile, multiple component carriers (CCs) can be assigned to the UEin the carrier aggregation system. For example, three 20 MHz CCs can beassigned to allocate a 60 MHz bandwidth to the UE. The CC includes a DLCC and a UL CC.

The carrier aggregation system can be divided into a contiguous carrieraggregation system in which carriers are contiguous to each other and anon-contiguous carrier aggregation system in which carriers areseparated from each other. Hereinafter, when it is simply called thecarrier aggregation system, it should be interpreted such that bothcases of contiguous CCs and non-contiguous CCs are included.

A CC which is a target when aggregating one or more CCs can directly usea bandwidth that is used in the legacy system in order to providebackward compatibility with the legacy system. For example, a 3GPP LTEsystem can support a carrier having a bandwidth of 1.4 MHz, 3 MHz, 5MHz, 10 MHz, 15 MHz, and 20 MHz, and a 3GPP LTE-A system can configure abroadband of 20 MHz or higher by using each carrier of the 3GPP LTEsystem as a CC. Alternatively, the broadband can be configured bydefining a new bandwidth without having to directly use the bandwidth ofthe legacy system.

A frequency band of a wireless communication system is divided into aplurality of carrier frequencies. Herein, the carrier frequency impliesa center frequency of a cell. Hereinafter, the cell may imply a downlinkfrequency resource and an uplink frequency resource. Alternatively, thecell may also imply combination of a downlink frequency resource and anoptional uplink frequency resource. In general, if carrier aggregation(CA) is not considered, uplink and downlink frequency resources canalways exist in pair in one cell.

In order to transmit and receive packet data through a specific cell,the UE first has to complete a configuration of the specific cell.Herein, the configuration implies a state of completely receiving systeminformation required for data transmission and reception for the cell.For example, the configuration may include an overall procedure thatrequires common physical layer parameters necessary for datatransmission and reception, media access control (MAC) layer parameters,or parameters necessary for a specific operation in a radio resourcecontrol (RRC) layer. A cell of which configuration is complete is in astate capable of immediately transmitting and receiving a packet uponreceiving only information indicating that packet data can betransmitted.

The cell in a state of completing its configuration can exist in anactivation or deactivation state. Herein, the activation implies thatdata transmission or reception is performed or is in a ready state. TheUE can monitor or receive a control channel (i.e., PDCCH) and a datachannel (i.e., PDSCH) of an activated cell in order to confirm aresource (e.g., frequency, time, etc.) allocated to the UE.

The deactivation implies that transmission or reception of traffic datais impossible and measurement or transmission/reception of minimuminformation is possible. The UE can receive system information (SI)required for packet reception from a deactivated cell. On the otherhand, the UE does not monitor or receive a control channel (i.e., PDCCH)and a data channel (i.e., PDSCH) of the deactivated cell in order toconfirm a resource (e.g., frequency, time, etc.) allocated to the UE.

A cell can be classified into a primary cell, a secondary cell, aserving cell, etc.

The primary cell implies a cell which operates at a primary frequency,and also implies a cell which performs an initial connectionestablishment procedure or a connection re-establishment procedure or acell indicated as the primary cell in a handover procedure.

The secondary cell implies a cell which operates at a secondaryfrequency, and is configured when an RRC connection is once establishedand is used to provide an additional radio resource.

The serving cell is configured with the primary cell in case of a UE ofwhich CA is not configured or which cannot provide the CA. If the CA isconfigured, the term ‘serving cell’ is used to indicate a set consistingof a primary cell and one or a plurality of cells among all secondarycells

That is, the primary cell implies one serving cell that provides asecurity input and NAS mobility information in an RRC establishment orre-establishment state. According to UE capabilities, it can beconfigured such that at least one cell constitutes a serving cell settogether with the primary cell, and in this case, the at least one cellis called the secondary cell.

Therefore, a set of serving cells assigned to only one UE can consist ofonly one primary cell, or can consist of one primary cell and at leastone secondary cell.

A primary component carrier (PCC) denotes a CC corresponding to aprimary cell. The PCC is a CC that establishes an initial connection (orRRC connection) with the BS among several CCs. The PCC serves forconnection (or RRC connection) for signaling related to a plurality ofCCs, and is a CC that manages UE context which is connection informationrelated to the UE. In addition, the PCC establishes connection with theUE, and thus always exists in an activation state when in an RRCconnected mode.

A secondary component carrier (SCC) denotes a CC corresponding to asecondary cell. That is, the SCC is a CC allocated to the UE in additionto the PCC. The SCC is an extended carrier used by the UE for additionalresource allocation or the like in addition to the PCC, and can bedivided into an activation state and a deactivation state.

A downlink CC corresponding to the primary cell is called a downlinkprimary component carrier (DL PCC), and an uplink CC corresponding tothe primary cell is called an uplink primary component carrier (UL PCC).In addition, in a downlink, a CC corresponding to the secondary cell iscalled a DL secondary CC (SCC). In an uplink, a CC corresponding to thesecondary cell is called a UL SCC.

The primary cell and the secondary cell have the following features.

First, the primary cell is used for PUCCH transmission.

Second, the primary cell is always activated, whereas the secondary cellis a cell which is activated/deactivated according to a specificcondition.

Third, when the primary cell experiences a radio link failure (RLF), RRCre-establishment is triggered, whereas when the secondary cellexperiences the RLF, the RRC re-establishment is not triggered.

Fourth, the primary cell can change by a handover procedure accompaniedby a random access channel (RACH) procedure or security keymodification.

Fifth, non-access stratum (NAS) information is received through theprimary cell.

Sixth, the primary cell always consists of a pair of a DL PCC and a ULPCC.

Seventh, for each UE, a different CC can be configured as the primarycell.

Eighth, a procedure such as reconfiguration, adding, and removal of theprimary cell can be performed by an RRC layer. When adding a newsecondary cell, RRC signaling can be used for transmission of systeminformation of a dedicated secondary cell.

A DL CC can construct one serving cell. Further, the DL CC can beconnected to a UL CC to construct one serving cell. However, the servingcell is not constructed only with one UL CC.

Activation/deactivation of a CC is equivalent to the concept ofactivation/deactivation of a serving cell. For example, if it is assumedthat a serving cell 1 consists of a DL CC 1, activation of the servingcell 1 implies activation of the DL CC 1. If it is assumed that aserving cell 2 is configured by connecting a DL CC 2 and a UL CC 2,activation of the serving cell 2 implies activation of the DL CC 2 andthe UL CC 2. In this sense, each CC can correspond to a cell.

The number of CCs aggregated between a downlink and an uplink may bedetermined differently. Symmetric aggregation is when the number of DLCCs is equal to the number of UL CCs. Asymmetric aggregation is when thenumber of DL CCs is different from the number of UL CCs. In addition,the CCs may have different sizes (i.e., bandwidths). For example, if 5CCs are used to configure a 70 MHz band, it can be configured such as 5MHz CC(carrier #0)+20 MHz CC(carrier #1)+20 MHz CC(carrier #2)+20 MHzCC(carrier #3)+5 MHz CC(carrier #4).

As described above, the carrier aggregation system can support multipleCCs unlike a single carrier system. That is, one UE may receive aplurality of PDSCHs through a plurality of DL CCs. In addition, the UEmay transmit ACK/NACK for the plurality of PDSCHs through one UL CC,e.g., UL PCC. That is, in the conventional single carrier system, sinceonly one PDSCH is received in one subframe, it is enough to transmit upto two pieces of HARQ ACK/NACK (hereinafter, simply called ACK/NACK)information. However, in the carrier aggregation system, since ACK/NACKfor a plurality of PDSCHs can be transmitted through one UL CC, a methodof transmitting the ACK/NACK is required.

Now, the conventional PUCCH format will be described.

The PUCCH carries various types of control information according to aformat. A PUCCH format 1 carries a scheduling request (SR). In thiscase, an on-off keying (OOK) scheme can be used. A PUCCH format 1acarries an ACK/NACK modulated using bit phase shift keying (BPSK) withrespect to one codeword. A PUCCH format 1b carries an ACK/NACK modulatedusing quadrature phase shift keying (QPSK) with respect to twocodewords. A PUCCH format 2 carries a channel quality indicator (CQI)modulated using QPSK. PUCCH formats 2a and 2b carry the CQI and theACK/NACK.

Table 1 shows a modulation scheme and the number of bits in a subframeaccording to a PUCCH format.

TABLE 1 PUCCH format Modulation scheme Number of bits per subframe,M_(bit) 1  N/A N/A 1a BPSK 1 1b QPSK 2 2  QPSK 20 2a QPSK + BPSK 21 2bQPSK + QPSK 22

FIG. 6 shows a channel structure of PUCCH formats 2/2a/2b for one slotin a normal CP case. As described above, the PUCCH formats 2/2a/2b areused in CQI transmission.

Referring to FIG. 6, in the normal CP case, SC-FDMA symbols 1 and 5 areused for a demodulation reference signal (DM RS) which is an uplinkreference signal. In an extended CP case, an SC-FDMA symbol 3 is usedfor the DM RS.

CQI information bits are channel coded, for example, with a coding rateof ½, to generate 20 coded bits. A Reed-Muller code can be used in thechannel coding. After scheduling, QPSK constellation mapping isperformed to generate QPSK modulation symbols (e.g., d₀ to d₄ in a slot0). Each QPSK modulation symbol is subjected to IFFT after beingmodulated by using a cyclic shift of a base RS sequence having a lengthof 12, and is then transmitted in each of 10 SC-FDMA symbols in asubframe. 12 equally-spaced cyclic shifts allow 12 different UEs to beorthogonally multiplexed on the same PUCCH RB. A DM RS sequence appliedto the SC-FDMA symbols 1 and 5 may be the base RS sequence having alength of 12.

FIG. 7 shows a PUCCH format 1a/1b for one slot in a normal CP case.Uplink reference signals are transmitted in 3^(rd) to 5^(th) SC-FDMAsymbols. In FIG. 7, w₀, w₁, w₂ and w₃ can be modulated in a time domainafter inverse fast Fourier transform (IFFT) modulation, or can bemodulated in a frequency domain before IFFT modulation.

In LTE, simultaneous transmission of ACK/NACK and CQI in the samesubframe may be enabled or disabled. In a case where simultaneoustransmission of the ACK/NACK and the CQI is disabled, a UE may need totransmit the ACK/NACK on a PUCCH of a subframe in which CQI feedback isconfigured. In this case, the CQI is dropped, and only the ACK/NACK istransmitted using the PUCCH formats 1a/1b.

Simultaneous transmission of the ACK/NACK and the CQI in the samesubframe can be achieved through UE-specific higher layer signaling.When simultaneous transmission is enabled, 1-bit or 2-bit ACK/NACKinformation needs to be multiplexed to the same PUCCH RB in a subframein which a BS scheduler permits simultaneous transmission of the CQI andthe ACK/NACK. In this case, it is necessary to preserve a single-carrierproperty having a low cubic metric (CM). A method of multiplexing theCQI and the ACK/NACK while preserving the single-carrier property isdifferent between a normal CP case and an extended CP case.

First, when 1-bit or 2-bit ACK/NACK and CQI are transmitted together byusing the PUCCH formats 2a/2b in the normal CP case, ACK/NACK bits arenot scrambled, and are subjected to BPSK (in case of 1 bit)/QPSK (incase of 2 bits) modulation to generate a single HARQ ACK/NACK modulationsymbol d_(HARQ). The ACK is encoded as a binary ‘1’, and the NACK isencoded as a binary ‘0’. The single HARQ ACK/NACK modulation symbold_(HARQ) is used to modulate a second RS symbol in each slot. That is,the ACK/NACK is signaled by using an RS.

FIG. 8 shows an example of constellation mapping of ACK/NACK in a normalCP case and a PUCCH format 2a/2b.

Referring to FIG. 8, NACK (or NACK/NACK in case of transmission of twoDL codewords) is mapped to +1. In discontinuous transmission (DTX) whichimplies a case where a UE fails to detect a DL grant, neither ACK norNACK is transmitted, and a default NACK is set in this case. The DTX isinterpreted as NACK by a BS, and causes DL retransmission.

Next, 1- or 2-bit ACK/NACK is joint-coded with CQI in an extended CPcase in which one RS symbol is used per slot.

FIG. 9 shows an example of joint coding between ACK/NACK and CQI in anextended CP case.

Referring to FIG. 9, a maximum number of bits of an information bitsupported by an RM code may be 13. In this case, a CQI information bitK_(cqi) may be 11 bits, and an ACK/NACK bit K_(ACK/NACK) may be 2 bits.The CQI information bit and the ACK/NACK information bit areconcatenated to generate a bit stream and thereafter may be subjected tochannel coding by the RM code. In this case, it is expressed such thatthe CQI information bit and the ACK/NACK information bit arejoint-coded. That is, the CQI information bit and the ACK/NACKinformation bit are joint-coded by an RM code into 20-bit coded bits.The 20-bit codeword generated in this process is transmitted through aPUCCH format 2 having the channel structure described in FIG. 6 (in anextended CP case, one RS symbol is used per slot unlike in FIG. 6).

In LTE, ACK/NACK and SR may be multiplexed and thus be simultaneouslytransmitted by using the PUCCH formats 1a/1b.

FIG. 10 shows a method of multiplexing ACK/NACK and SR.

Referring to FIG. 10, when ACK/NACK and SR are transmittedsimultaneously in the same subframe, a UE transmits the ACK/NACK byusing an allocated SR resource. In this case, the SR implies positiveSR. In addition, the UE may transmit ACK/NACK by using an allocatedACK/NACK resource. In this case, the SR implies negative SR. That is,according to which resource is used to transmit ACK/NACK in a subframein which the ACK/NACK and the SR are simultaneously transmitted, a BScan identify not only the ACK/NACK but also whether the SR is positiveSR or negative SR.

FIG. 11 shows constellation mapping when ACK/NACK and SR aresimultaneously transmitted.

Referring to FIG. 11, DTX/NACK and positive SR are mapped to +1 of aconstellation map, and ACK is mapped to −1.

Meanwhile, in the LTE TDD system, a UE can feed back multiple ACK/NACKfor multiple PDSCHs to a BS. This is because the UE can receive themultiple PDSCHs in multiple subframes, and can transmit ACK/NACK for themultiple PDSCHs in one subframe. In this case, there are two types ofACK/NACK transmission methods as follows.

The first method is ACK/NACK bundling. The ACK/NACK bundling is aprocess of combining ACK/NACK bits for multiple data units by using alogical AND operation. For example, if the UE decodes all the multipledata units successfully, the UE transmits only one ACK bit. Otherwise,if the UE fails in decoding (or detecting) any one of the multiple dataunits, the UE may transmit NACK or may transmit no signal as ACK/NACK.

The second method is ACK/NACK multiplexing. With ACK/NACK multiplexing,the content and meaning of the ACK/NACK for the multiple data units canbe identified by combining a PUCCH resource used in actual ACK/NACKtransmission and one of QPSK modulation symbols.

For example, it is assumed that up to two data units can be transmitted,and one PUCCH resource can carry two bits. It is also assumed that anHARQ operation for each data unit can be managed by one ACK/NACK bit. Inthis case, the ACK/NACK can be identified at a transmitting node (e.g.,a BS) which transmits the data unit according to Table 2 below.

TABLE 2 HARQ-ACK(0), HARQ-ACK(1) n⁽¹⁾ _(PUCCH) b(0), b(1) ACK, ACK n⁽¹⁾_(PUCCH, 1) 1, 1 ACK, NACK/DTX n⁽¹⁾ _(PUCCH, 0) 0, 1 NACK/DTX, ACK n⁽¹⁾_(PUCCH, 1) 0, 0 NACK/DTX, NACK n⁽¹⁾ _(PUCCH, 1) 1, 0 NACK, DTX n⁽¹⁾_(PUCCH, 0) 1, 0 DTX, DTX N/A N/A

In Table 2, HARQ-ACK(i) indicates an ACK/NACK result for a data unit i.In the above example, two data units may exist, i.e., a data unit 0 anda data unit 1. In Table 2, DTX implies that there is no data unittransmission for the HARQ-ACK(i). Alternatively, it implies that areceiving end (e.g., a UE) fails to detect the data unit for theHARQ-ACK(i). n⁽1⁾ _(PUCCH,X) indicates a PUCCH resource used in actualACK/NACK transmission. There are up to 2 PUCCH resources, that is, n⁽1⁾_(PUCCH,0) and n⁽1⁾ _(PUCCH,1). b(0) and b(1) denote 2 bits delivered bya selected PUCCH resource. A modulation symbol transmitted using thePUCCH resource is determined by b(0) and b(1).

For one example, if the receiving end successfully receives two dataunits and decodes the received data units, the receiving end has totransmit two bits b(0) and b(1) in a form of (1, 1) by using a PUCCHresource n⁽1⁾ _(PUCCH,1). For another example, it is assumed that thereceiving end receives two data units, and in this case, the receivingend fails to decode 1^(st) data unit and successfully decodes 2^(nd)data unit. Then, the receiving end has to transmit (0, 0) by using n⁽1⁾_(PUCCH,1).

As such, according to a method in which the content (or meaning) ofACK/NACK is linked to a combination of a PUCCH resource and the contentof an actual bit transmitted using the PUCCH resource, ACK/NACKtransmission for the multiple data units is enabled by using a singlePUCCH resource.

In the ACK/NACK multiplexing method, if at least one ACK exists for alldata units, NACK and DTX are basically coupled as NACK/DTX. This isbecause a combination of a PUCCH resource and a QPSK symbol is notenough to cover all ACK/NACK combinations based on decoupling of theNACK and the DTX.

In the aforementioned ACK/NACK bundling or channel selection, the totalnumber of PDSCHs for which ACK/NACK is transmitted by the UE isimportant. If the UE fails to receive some of the plurality of PDCCHsfor scheduling a plurality of PDSCHs, an error occurs in the totalnumber of PDSCHs for which the ACK/NACK is transmitted, and thusACK/NACK may be transmitted erroneously. To correct this error, a TDDsystem transmits the PDCCH by including a downlink assignment index(DAI). The DAI reports a counting value by counting the number of PDCCHsfor scheduling the PDSCHs.

Hereinafter, a method of coding an uplink channel for a PUCCH format 2will be described.

Table 3 below shows an example of a (20,A) RM code used in channelcoding of a PUCCH format 2. Herein, A may denote the number of bits(i.e., K_(cqi)+K_(ACK/NACK)) of a bit stream in which a CQI informationbit and an ACK/NACK information bit are concatenated. If the bit streamis denoted by a₀,a₁,a₂, . . . ,a_(A-1), the bit stream can be used as aninput of a channel coding block using the (20,A) RM code.

TABLE 3 i M_(i, 0) M_(i, 1) M_(i, 2) M_(i,) ₃ M_(i, 4) M_(i, 5) M_(i,) ₆M_(i, 7) M_(i, 8) M_(i, 9) M_(i, 10) M_(i, 11) M_(i, 12) 0 1 1 0 0 0 0 00 0 0 1 1 0 1 1 1 1 0 0 0 0 0 0 1 1 1 0 2 1 0 0 1 0 0 1 0 1 1 1 1 1 3 10 1 1 0 0 0 0 1 0 1 1 1 4 1 1 1 1 0 0 0 1 0 0 1 1 1 5 1 1 0 0 1 0 1 1 10 1 1 1 6 1 0 1 0 1 0 1 0 1 1 1 1 1 7 1 0 0 1 1 0 0 1 1 0 1 1 1 8 1 1 01 1 0 0 1 0 1 1 1 1 9 1 0 1 1 1 0 1 0 0 1 1 1 1 10 1 0 1 0 0 1 1 1 0 1 11 1 11 1 1 1 0 0 1 1 0 1 0 1 1 1 12 1 0 0 1 0 1 0 1 1 1 1 1 1 13 1 1 0 10 1 0 1 0 1 1 1 1 14 1 0 0 0 1 1 0 1 0 0 1 0 1 15 1 1 0 0 1 1 1 1 0 1 10 1 16 1 1 1 0 1 1 1 0 0 1 0 1 1 17 1 0 0 1 1 1 0 0 1 0 0 1 1 18 1 1 0 11 1 1 1 0 0 0 0 0 19 1 0 0 0 0 1 1 0 0 0 0 0 0

Bits b₀,b₁,b₂, . . . ,b_(B-1) which are channel-coded by an RM code canbe generated by Equation 1 below.

$\begin{matrix}{b_{i} = {\sum\limits_{n = 0}^{A - 1}{\left( {a_{n} \cdot M_{i,n}} \right){mod}\; 2}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In Equation 1 above, i=0,1,2, . . . ,B−1, where B=20.

Channel-coded bits are mapped to a code-time-frequency resource.

FIG. 12 shows an example of mapping channel-coded bits to acode-time-frequency resource.

Referring to FIG. 12, among channel-coded 20 bits, first 10 bits andlast 10 bits are mapped to different code-time-frequency resources. Inparticular, the first 10 bits and the last 10 bits are transmitted bybeing separated significantly in a frequency domain for frequencydiversity.

Now, an example of an uplink channel coding method in LTE-A will bedescribed.

As described above, in LTE, if UCI is transmitted with a PUCCH format 2,CSI of up to 13 bits is subjected to RM coding by using the (20, A) RMcode of Table 3. Otherwise, if the UCI is transmitted through a PUSCH,CQI of up to 11 bits is subjected to RM coding through (32, A) RM codeof Table 4 below, and truncation or circular repetition is performed toconform to a code rate at which transmission is performed through thePUSCH.

TABLE 4 i M_(i, 0) M_(i, 1) M_(i, 2) M_(i, 3) M_(i, 4) M_(i, 5) M_(i, 6)M_(i, 7) M_(i, 8) M_(i, 9) M_(i, 10) 0 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 0 00 0 0 0 1 1 2 1 0 0 1 0 0 1 0 1 1 1 3 1 0 1 1 0 0 0 0 1 0 1 4 1 1 1 1 00 0 1 0 0 1 5 1 1 0 0 1 0 1 1 1 0 1 6 1 0 1 0 1 0 1 0 1 1 1 7 1 0 0 1 10 0 1 1 0 1 8 1 1 0 1 1 0 0 1 0 1 1 9 1 0 1 1 1 0 1 0 0 1 1 10 1 0 1 0 01 1 1 0 1 1 11 1 1 1 0 0 1 1 0 1 0 1 12 1 0 0 1 0 1 0 1 1 1 1 13 1 1 0 10 1 0 1 0 1 1 14 1 0 0 0 1 1 0 1 0 0 1 15 1 1 0 0 1 1 1 1 0 1 1 16 1 1 10 1 1 1 0 0 1 0 17 1 0 0 1 1 1 0 0 1 0 0 18 1 1 0 1 1 1 1 1 0 0 0 19 1 00 0 0 1 1 0 0 0 0 20 1 0 1 0 0 0 1 0 0 0 1 21 1 1 0 1 0 0 0 0 0 1 1 22 10 0 0 1 0 0 1 1 0 1 23 1 1 1 0 1 0 0 0 1 1 1 24 1 1 1 1 1 0 1 1 1 1 0 251 1 0 0 0 1 1 1 0 0 1 26 1 0 1 1 0 1 0 0 1 1 0 27 1 1 1 1 0 1 0 1 1 1 028 1 0 1 0 1 1 1 0 1 0 0 29 1 0 1 1 1 1 1 1 1 0 0 30 1 1 1 1 1 1 1 1 1 11 31 1 0 0 0 0 0 0 0 0 0 0

Meanwhile, in LTE-A, a PUCCH format 3 is introduced to transmit UCI(ACK/NACK and SR) of up to 21 bits (i.e., the number of bits beforechannel coding as information bits).

The PUCCH format 3 is used to perform transmission based on blockspreading. That is, a modulation symbol sequence obtained by modulatinga multi-bit ACK/NACK is transmitted by being spread, by using a blockspreading coding, in a time domain.

FIG. 13 shows an example of a channel structure of a PUCCH format 3.

Referring to FIG. 13, a modulation symbol sequence {d1, d2, . . . } isspread in a time domain by applying a block spreading code. The blockspreading code may be an orthogonal cover code (OCC). Herein, amodulation symbol sequence may be a sequence of modulation symbols inwhich multi-bit ACK/NACK information bits are subjected to channelcoding (by using an RM code, a TBCC, a punctured RM code, etc.) togenerate an ACK/NACK coded bit and in which the ACK/NACK coded bits aremodulated (e.g., QPSK). The sequence of the modulation symbols istransmitted after mapping to data symbols of a slot through fast Fouriertransform (FFT) and inverse fast Fourier transform (IFFT). Although itis exemplified in FIG. 13 that two RS symbols are present in one slot, acase where 3 RS symbols are present is also possible, and in this case,a block spreading code having a length of 4 may be used.

Such a PUCCH format 3 can transmit a channel-coded bit of 48 bits in anormal CP. If a UCI bit (i.e., information bit) is less than or equal to11 bits, the (32, A) RM coding of Table 4 is used, and circularrepetition is used to conform to the number of coded bits of the PUCCHformat 3. As shown in Table 4, since the (32, A) RM code has only 11basis sequences, if a UCI bit is greater than 11 bits, dual RM codingusing two (32, A) RM codes is used.

FIG. 14 shows an example of a dual RM coding process.

Referring to FIG. 14, if a UCI bit stream (i.e., information bits)exceeds 11 bits, segmentation is used to generate a segmented bit stream(called a segment). In this case, each of a segment 1 and a segment 2 isless than or equal to 11 bits. Each of the segments 1 and 2 isinterleaved or concatenated through the (32, A) RM coding. Thereafter,truncation or circular repetition is transmitted after truncation orcircular repetition is performed to conform to the number of coded bitsof the PUCCH format 3.

Now, the present invention will be described.

In LTE, if periodic CQI transmission and ACK/NACK transmission collidewith each other in a specific subframe, it may be configured such thatsimultaneous transmission of the period CQI and the ACK/NACK ispossible. If the specific subframe is a subframe without PUSCHtransmission, ACK/NACK is transmitted by being multiplexed in such amanner that phase modulation is performed on a second reference signalsymbol of a PUCCH format 2 in which CQI is transmitted.

However, if PUSCH transmission is not performed in the specific subframeand if periodic CQI and multiple ACK/NACK (e.g., multiple ACK/NACK formultiple PDSCHs) transmission is required, such a conventional method isnot appropriate. This is because it is difficult to guaranteereliability when using the conventional method since an ACK/NACKinformation amount is great. Therefore, there is a need for a new methodfor multiplexing and transmitting periodic CSI and ACK/NACK through aPUCCH in a subframe without PUSCH transmission.

The present invention proposes a multiplexing method for a case wheresimultaneous transmission is configured to the same uplink controlchannel by multiplexing periodic CSI and ACK/NACK and an uplink controlchannel selection method based on a UCI configuration.

Hereinafter, CSI may be limited to periodic CSI except for aperiodicCSI. Although it is exemplified to use RM coding as channel codinghereinafter for convenience of explanation, the present invention is notlimited thereto. In addition, the present invention may also include CQItransmission for a case of a configuration in which a plurality of CSIsare simultaneously transmitted. In addition, although dual RM codingusing 2 RM coding blocks is exemplified when using multiple-RM coding,this is not for limiting to use two or more RM coding blocks. Although aPUCCH format 3 is exemplified as a UL channel in which channel-codedcontrol information is transmitted, the present invention is not limitedthereto. Thus, the present invention may also apply to a case where thePUCCH format 3 is modified. For example, the present invention may alsoapply to a modified PUCCH format 3 in which a spreading factor isdecreased from the PUCCH format 3. In addition, optionally, the presentinvention may also apply to a case where UCI is transmitted through aPUSCH.

I. Distributed Arrangement Based on Priority Per UCI Type whenPerforming UCI Channel Coding-UCI Joint Coding.

RM coding is characterized in that decoding performance is good whencoding is performed with a basis sequence having a low basis sequenceindex (BSI). In Table 4, a basis sequence having a lowest BSI isM_(i,0), and a basis sequence having a highest BSI is M_(i,10).Therefore, if an importance thereof is different according to a UCItype, UCI having a high importance is preferably arranged such thatcoding is performed by using a basis sequence having a low BSI. That is,preferably, multiplexing is performed by consecutively concatenating abit stream order of RM coding in order of UCI having a high importance.

For example, when an importance is high in order of ACK/NACK, SR, andCSI among UCIs, an input bit of RM coding is arranged in a concatenatedmanner in order of ACK/NACK, SR, and CSI. If SR transmission is notrequired, it is arranged in order of ACK/NACK and CSI. In this case, RI,PTI, CQI, etc., additionally constructing the CSI may also have adifferent importance. In this case, the CSI may also construct the inputbit of the RM coding in order of its importance.

An importance for each UCI type may correspond to an order of CSI,ACK/NACK, and SR, or an order of RI, ACK/NACK, SR, PTI, and CQI, or anorder of RI, PTI, ACK/NACK, SR, and CQI. The importance for each UCItype may be determined by various criteria such as an influence exertedto a system throughput, an efficiency of UL control channel resourceutilization, etc.

If a sum of payloads of UCI constituting the input bit stream of the RMcoding exceeds 11 bits (i.e., if a UCI information bit exceeds 11 bits),double RM(dual RM) is used since a basis sequence is insufficient incase of single RM. In this case, a mechanism of segmenting concatenatedUCI bit streams according to the aforementioned importance for each UCIis a matter.

FIG. 15 shows an example of a method of segmenting a UCI bit stream.

Referring to FIG. 15(a), when a leftmost bit is a most significant bit(MSB), a UCI bit stream concatenated in order of ACK/NACK and CSI fromthe left is simple-segmented with the same number of bits for example.Each of a segment 1 and a segment 2 which are generated through thesimple segmentation is RM-coded with a (32, A) RM code. As such, whenthe UCI bit stream is simple-segmented, there may be a case where UCIhaving a high importance is arranged to be coded with a basis sequenceof an RM code having a higher BSI than UCI having a low importance. Forexample, even if ACK/NACK has a higher importance than CSI, when theACK/NACK is simple-segmented to the segment 1 and the CSI issimple-segmented to the segment 2, there may be a case where right-sidebits of the segment 1 are coded with a basis sequence of an RM codehaving a higher BSI than left-side bits of the segment 2.

In order to avoid this, as shown in FIG. 15(b), the present inventionproposes to arrange UCI having a high importance (e.g., ACK/NACK bits)to a left side (i.e., an MSB side) of each of the segment 1 and thesegment 2 in a distributed manner, and to arrange UCI having a lowimportance (e.g., CSI bits) of each segment subsequently in adistributed manner (this is called distributed segmentation ordistributed mapping). Each of the segment 1 and the segment 2 which aregenerated through the distributed segmentation is RM-coded with a (32,A) RM code. When using such a distributed segmentation method, anACK/NACK bit in each segment is coded with an RM basis sequence having alower BSI. Therefore, decoding performance of a receiving side can beincreased. The distributed segmentation can be implemented byintroducing an interleaver before segmentation. The aforementionedconcept will be described in a greater detail.

FIG. 16 shows a channel coding method using double RM according to anembodiment of the present invention.

If a PUCCH format 3 is configured by a higher layer and is used to feedback ACK/NACK, the ACK/NACK to be fed back is configured with aconcatenation of ACK/NACK bits of respective serving cells. 1-bitACK/NACK information a_(k) is used for one downlink subframe of a cellwhich is set to a single-codeword transmission mode. 2-bit ACK/NACKinformation a_(k), a_(k+1) is used for one downlink subframe of a cellwhich is set to another transmission mode, i.e., a multiple-codewordtransmission mode, where a_(k) corresponds to a codeword 0, and a_(k+1)corresponds to a codeword 1. If spatial bundling is applied, the 1-bitACK/NACK information may be used.

If the PUCCH format 3 is used for transmission of ACK/NACK feedback,N^(PUCCHformat3) _(A/N) denotes the number of bits of ACK/NACK (SR maybe included) and/or periodic CSI. In FIG. 16, a UCI bit stream consistsof N^(PUCCHformat3) _(A/N) bits. The UCI bit stream consisting of theN^(PUCCHformat3) _(A/N) bits is aligned such as

a₀, a₁, a₂, …  ,,a_(N_(A/N)^(PUCCH  format  3) − 1).

Concatenated ACK/NACK bits, SR bits, and CSI bits may exist in

a₀, a₁, a₂, …  ,,a_(N_(A/N)^(PUCCH  format  3) − 1).

The concatenated ACK/NACK bits are obtained as follows.

In case of FDD, a bit sequence

a₀, a₁, a₂, …  ,,a_(N_(A/N)^(PUCCH  format  3) − 1)

may be a result of a concatenation of ACK/NACK bits for each of cellsthrough a process of the following table. In the tables below, ACK/NACKis denoted by HARQ-ACK.

TABLE 5 1. Set c=0 - Cell index: Lower indices correspond to lower RRCincides of corresponding cell 2. Set j=0 - HARQ-ACK bit index 3. SetN_(Cells) ^(DL) as the number of cells assigned to UE by higher layer while c < N_(Cells) ^(DL) if transmission mode which is set to Cell cis any one of {1,2,5,6,7}, 1-bit ACK/NACK is fed back for this cella_(j) = HARQ-ACK bit of this cell j = j + 1 else a_(j) = HARQ-ACK bitcorresponding to first codeword j = j + 1 a_(j) = HARQ-ACK bitcorresponding to second codeword j = j + 1  end if  c = c + 1 end while

ACK/NACK bits may be concatenated in order of ACK/NACK for a primarycell, i.e., a cell with c=0 and ACK/NACK for a secondary cell.

In case of TDD, a bit sequence a₀, a₁, a₂, . . . , a_(N) _(A/N)_(PUCCHformat3) ⁻¹ may be acquired by the following table for each ofcells and for each of subframes. In the table below, N^(DL) _(cells)denotes the number of cells assigned to a UE by a higher layer, andB^(DL) _(c) denotes the number of DL subframes in which ACK/NACK must befed back in a cell c by the UE. The number of ACK/NACK bits to bedelivered by the UE is calculated by the following table.

TABLE 6 1. Set k=0 - Counter of HARQ-ACK bits 2. Set c=0 - Cell index:Lower indices correspond to lower RRC incides of corresponding cell 3.while c < N_(Cells) ^(DL) set l = 0; while l < B_(c) ^(DL) iftransmission mode which is set to Cell c is any one of {1,2,5,6,7},1-bit ACK/NACK is fed back for this cell k = k + 1 else k = k + 2 end if c = c + 1 end while

If k≦20, HARQ-ACK bits are multiplexed by the following table.

TABLE 7 1. Set c=0 - Cell index: Lower indices correspond to lower RRCincides of corresponding cell 2. Set j=0 - HARQ-ACK bit index 3. while c< N_(Cells) ^(DL) set 1 = 0; while l < B_(c) ^(DL) if transmission modewhich is set to Cell c is any one of {1,2,5,6,7}, 1-bit ACK/NACK is fedback for this cell õ_(j) ^(ACK) = o_(c,l) ^(ACK) HARQ-ACK bit of thiscell j = j + 1 else {tilde over ([)}õ_(j) ^(ACK), õ_(j+1) ^(ACK)] =[o_(c,2l) ^(ACK), o_(c,2l+1) ^(ACK),] HARQ-ACK bit of this cell j = j +2 end if  l=l+1  end while  c = c + 1 end while

If k>20, spatial bundling is applied to all subframes of all cells. Inaddition, HARQ-ACK bits are multiplexed by the following table.

TABLE 8 1. Set c=0 - Cell index: Lower indices correspond to lower RRCincides of corresponding cell 2. Set j=0 - HARQ-ACK bit index 3. while c< N_(Cells) ^(DL) set 1 = 0; while l < B_(c) ^(DL) if transmission modewhich is set to Cell c is any one of {1,2,5,6,7}, 1-bit ACK/NACK is fedback for this cell õ_(j) ^(ACK) = o_(c,l) ^(ACK), HARQ-ACK bit of thiscell j = j + 1 else õ_(j) ^(ACK) = o_(c,l) ^(ACK), Binary AND operationof HARQ ACK bits corresponding to first codeword and second codeword ofthis cell j = j + 1 end if  l=l+1  end while  c = c + 1 end while

If the PUCCH format 3 is used for ACK/NACK feedback and SR transmissionis set in a subframe in which the ACK/NACK feedback is performed, onebit for an SR (if 1, a positive SR, and if 0, a negative SR) isadditionally concatenated at the end of ACK/NACK bits of theconcatenated bit.

If the PUCCH format 3 is used for ACK/NACK feedback and periodic CSItransmission is assigned by a higher layer in a subframe for performingthe ACK/NACK feedback, periodic CSI bits are additionally concatenatedat the end of concatenated ACK/NACK bits (if an SR bit is added, afterthe SR bit). If the SR and the period CSI are concatenated at the end ofthe concatenated ACK/NACK bits, in the aforementioned process,N^(PUCCHformat3) _(A/N) is a value indicating a sum of the number ofbits of the concatenated ACK/NACK bits and the number of bits of the SRand the periodic CSI.

If N^(PUCCHformat3) _(A/N) is less than or equal to 11 bits, the bitsequence

a₀, a₁, a₂, …  ,,a_(N_(A/N)^(PUCCH  format  3) − 1)

is obtained by setting to a_(i)=õ_(i) ^(ACK).

If N^(PUCCHformat3) _(A/N) is less than or equal to 11 bits, the bitsequence

a₀, a₁, a₂, …  ,,a_(N_(A/N)^(PUCCH  format  3) − 1)

is encoded by the following equation.

$\begin{matrix}{{\overset{\sim}{b}}_{i} = {\underset{n = 0}{\sum\limits^{N_{A/N}^{{PUCCH}\mspace{11mu} {format}\mspace{11mu} 3} - 1}}{\left( {a_{n} \cdot M_{i,n}} \right){mod}\; 2}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

Herein, i is 0, 1, 2, . . . , 31, and basis sequences M_(i,n) aredefined by Table 4.

An output bit sequence b₀,b₁,b₂, . . . ,b_(B-1) is obtained by thefollowing equation through circular repetition of a sequence {tilde over(b)}₀,{tilde over (b)}₁,{tilde over (b)}₂, . . . ,{tilde over (b)}₃₁.

b_(i)=b_((i mod 32))  [Equation 3]

Herein, i=0, 1, 2, . . . , B−1, where B=4N^(RB) _(sc). N^(RB) _(sc)denotes a resource block size in a frequency domain expressed with thenumber of subcarriers.

If N^(PUCCHformat3) _(A/N) is greater than 11 bits and less than orequal to 22 bits, the bit sequence

a₀, a₁, a₂, …  ,,a_(N_(A/N)^(PUCCH  format  3) − 1)

is obtained by the following equation.

a_(i/2)=õ_(i) ^(ACK), i is an even number  [Equation 4]

a┌N_(A/N) ^(PUCCH format3)/2┐_(+(i-1)/2)=õ_(i) ^(ACK), i is an oddnumber

That is, Equation 4 above corresponds to a process of interleaving a UCIbit stream in FIG. 16. According to Equation 4, concatenated ACK/NACKbits arranged to a front portion are arranged in a distributed manner ina UCI bit stream consisting of N^(PUCCHformat3) _(A/N) bits. If a bitsequence

a₀, a₁, a₂, …  ,,a_(⌈N_(A/N)^(PUCCH  format  3)/2⌉ − 1)

is a segment 1 and a bit sequence

a_(⌈N_(A/N)^(PUCCH  format  3)/2⌉), a_(⌈N_(A/N)^(PUCCH  format  3)/2⌉ + 1), a_(⌈N_(A/N)^(PUCCH  format  3)/2⌉ + 2), …  ,,a_(N_(A/N)^(PUCCH  format  3) − 1)

is a segment 2, a bit stream

(i.e., a₀, a₁, a₂, …  ,,a_(N_(A/N)^(PUCCH  format  3) − 1))

obtained by interleaving the UCI bit stream by using Equation 4 is a bitstream in which the segment 1 and the segment 2 are concatenated in thatorder, ACK/NACK is arranged to an MSB side of each of the segments 1 and2, and periodic CSI is arranged in an LBS side. More specifically,according to Equation 4, bits of which a bit index i is an even numberin the UCI bit stream are arranged in the 1^(st) segment in an orderlymanner, and bits of which a bit index is an odd number in the UCI bitstream are arranged in the 2^(nd) segment in an orderly manner. Since abit stream interleaved in this manner is greater than 11 bits and lessthan or equal to 22 bits, it is segmented into the segment 1 and thesegment 2 to perform double RM, and thus double RM coding is performedby the following equation.

                                     [Equation  5]$\mspace{79mu} {{\overset{\sim}{b}}_{i} = {\sum\limits_{n = 0}^{{\lceil{N_{A/N}^{{PUCCH}\mspace{11mu} {format}\mspace{11mu} 3}/2}\rceil} - 1}{\left( {a_{n} \cdot M_{i,n}} \right){mod}\; 2}}}$${\overset{\approx}{b}}_{i} = {\quad{\sum\limits_{n = 0}^{N_{A/N}^{{PUCCH}\mspace{11mu} {format}\mspace{11mu} 3} - {\lceil{N_{A/N}^{{PUCCH}\mspace{11mu} {format}\mspace{11mu} 3}/2}\rceil} - {1\quad}}\left( {{a_{{\lceil{N_{A/N}^{{PUCCH}\mspace{11mu} {format}\mspace{11mu} 3}/2}\rceil} + n} \cdot \left. \quad M_{i,n} \right)}{mod}\; 2} \right.}}$

Herein, i=0,1,2, . . . ,23, and basis sequences M_(i,n) are defined byTable 4.

As shown in Equation 5 above, according to the present invention,ACK/NACK bits of the segments 1 and 2 are coded with a basis sequence ofan RM code having a lower BSI, and periodic CSI is coded with a basissequence of an RM code having a relatively higher BSI. Therefore, evenif multiple ACK/NACK and periodic CSI are transmitted together, adecoding performance of ACK/NACK having a high importance can beguaranteed.

A bit sequence b₀,b₁,b₂, . . . ,b_(B-1) is obtained bycross-concatenating bit sequences {tilde over (b)}₀,{tilde over(b)}₁,{tilde over (b)}₂, . . . ,{tilde over (b)}₂₃ and {tilde over({tilde over (b)})}₀,{tilde over ({tilde over (b)})}₁,{tilde over({tilde over (b)})}₂, . . . ,{tilde over ({tilde over (b)})}₂₃ by 2 bitsas shown in the following table. That is, when a channel-coded UCI isinterleaved, the interleaving can be expressed such that 2 bits obtainedfrom each of bits of the 1^(st) and 2^(nd) segments which arechannel-coded are concatenated alternately as shown in Table 9 below.Herein, B=4 N^(RB) _(sc).

Set i, j = 0 while i < 4 · N_(SC) ^(RB)  b_(i)= {tilde over (b)}_(j),b_(i+1) = {tilde over (b)}_(j+1) b_(i+2) = {tilde over ({tilde over(b)})}_(j), b_(i+3) = {tilde over ({tilde over (b)})}_(j+1)  i = i + 4 j = j + 2 end while

FIG. 17 shows the interleaver of FIG. 16 in detail.

As to B bit streams, the interleaver writes a column preferentially(i.e., a mechanism of moving to a next row index after increasing acolumn index), and reads a row preferentially (i.e., a mechanism ofmoving to a next column index after increasing a row index). When thenumber of columns of the interleaver is C, C=2 in case of double RM. Iftwo or more RM coding blocks are used, C is the number of RM codingblocks.

As shown in FIG. 17, a UCI bit stream consisting of B(=N^(PUCCHformat3)_(A/N)) bits is subjected to interleaving so that bits having aneven-numbered bit index are aligned in an MSB side, and bits having anodd-numbered bit index are aligned in an LSB side. An interleaved bitstream

a₀, a₁, a₂, …  ,,a_(N_(A/N)^(PUCCH  format  3) − 1)

may be segmented into a segment consisting of only bits having aneven-numbered bit index and a segment consisting of only bits having anodd-numbered bit index in the UCI bit stream. Alternatively,interleaving and segmenting may be performed simultaneously.

FIG. 18 is a flowchart of the method described with reference to FIG. 16and FIG. 17.

Referring to FIG. 18, a UE generates a concatenated bit stream in orderof 1^(st) UCI and 2^(nd) UCI (step S10). If the number of bits of theconcatenated bit stream has a specific range, the UE segments theconcatenated bit stream after interleaving in order of a 1^(st) segmentconsisting of odd-numbered bits (if a bit index of an MSB is 0 and issequentially increased in the concatenated bit stream, the odd-numberedbits are bits of which a bit index is an even number) and a 2^(nd)segment consisting of even-numbered bits (if a bit index of an MSB is 0and is sequentially increased in the concatenated bit stream, theeven-numbered bits are bits of which a bit index is an odd number) (stepS20), and performs RM coding on the 1^(st) segment and the 2^(nd)segment (step S30). Such a method can be applied to channel coding andmultiplexing of ACK/NACK and periodic CSI if a PUCCH format 3 is usedfor ACK/NACK feedback and periodic CSI transmission is scheduled in asubframe for performing the ACK/NACK feedback (SR may also be included).Accordingly, as shown in FIG. 16, ACK/NACK and CSI are uniformlydistributed to RM coding blocks in both sides. In each RM coding, codingis achieved such that the ACK/NACK is coded with a basis sequence of anRM code having a low BSI, and the CSI is coded with a basis sequence ofan RM code having a high BSI.

Meanwhile, in case of ACK/NACK, additional channel coding may beperformed to satisfy an error rate required per information. That is,1^(st) channel coding may be first performed on the ACK/NACK, and 2^(nd)channel coding may be performed together with other UCIs. For example,after performing repetition coding in case of a 1-bit indicator per CCand performing simplex coding in case of a 2-bit indicator per CC, jointcoding may be performed together with other UCIs.

II. Method of Securing ACK/NACK Transmission Resource in UCI JointCoding.

Periodic CSI is reported according to a period configured by a higherlayer signal between a BS and a UE. Therefore, there is no ambiguitybetween the BS and the UE as to a presence/absence of CSI. On the otherhand, in case of ACK/NACK, there is a possibility that the UE cannotreceive scheduling information for scheduling a PDSCH. In this case,although the BS expects ACK/NACK for the PDSCH in a UL subframe in whichthe ACK/NACK is transmitted, since the UE fails to receive thescheduling information itself, an erroneous situation may occur in whichthe ACK/NACK is not transmitted at all. When the ACK/NACK and the CSIare transmitted through multiplexing, if transmission is performed byusing the same format (e.g., PUCCH format 3) and the same resource asthose used in case of transmitting only the CSI, in the aforementionederroneous situation, ambiguity may occur for the BS as to whether UCI isACK/NACK+CSI or includes only the CSI.

That is, in case of UCI information having no ambiguity in itspresence/absence, whether a bit field position for corresponding UCIinformation exists can be determined according to the presence/absence.However, in case of UCI having ambiguity in its presence/absence, as onemethod of decreasing an error, a bit field for the UCI information issecured irrespective of the presence/absence of the UCI information.

For example, in a UL subframe in which the UE does not transmit periodicCSI, there is no error even if ACK/NACK is transmitted by using allresources in a PUCCH format assigned to the UE. This is because there isno ambiguity between the BS and the UE as to a presence/absence of theperiodic CSI. On the other hand, if CSI is transmitted in a UL subframein which ACK/NACK is not transmitted, even if there is no ACK/NACK to betransmitted, CSI is mapped to the remaining resources other than aresource to be mapped with maximum ACK/NACK information that can begenerated in a corresponding configuration.

FIG. 19 shows an example of a resource arrangement when ACK/NACK and CSIare transmitted through multiplexing.

Referring to FIG. 19(a), when the ACK/NACK and the CSI are present andare transmitted through multiplexing, concatenating is achieved in orderof the ACK/NACK and the CSI, the ACK/NACK is coded with an RM basissequence having a low BSI, and the CSI is coded with an RM basissequence having a high BSI. If the ACK/NACK is not present and only theCSI is present, CSI bits are arranged in a state where a bit field ofthe ACK/NACK is empty. Therefore, since a resource efficiency isdecreased, and CSIs cannot be coded with the RM basis sequence having alow BSI, there may be a problem in which a decoding performancedeteriorates. In addition, if only the ACK/NACK is present, the ACK/NACKis arranged to an ACK/NACK bit field or an entire bit field.

As one method of solving the aforementioned problem, as shown in FIG.19(b), UCI having no ambiguity in a presence/absence, e.g., CSI, may bearranged first, followed by UCI having ambiguity, e.g., ACK/NACK. Inthis case, when only the CSI is present, the CSI is coded by using an RMbasis sequence having a low BSI, and thus there is an advantage in thata decoding performance is increased.

In case of SR, a subframe in which the SR can be transmitted isconfigured similarly to the CSI, and thus there is no ambiguity in apresence/absence of an SR bit. Therefore, it is possible to conform tothe aforementioned rule. For example, when the SR and the ACK/NACK aretransmitted simultaneously, the SR is arranged first, and the ACK/NACKis arranged later. When the SR and the CSI are transmittedsimultaneously, both of them do not have ambiguity, and thus any one ofan order of SR and CSI or an order of CSI and SR can be used. When theSR, the CSI, and the ACK/NACK are transmitted simultaneously, they arearranged in order of the CSI, the SR, and the ACK/NACK or in order ofthe SR, the CSI, and the ACK/NACK.

Meanwhile, for backward compatibility with the legacy system, even ifthe SR is UCI not having ambiguity, the SR may be exceptionally arrangednext to the ACK/NACK. Therefore, when the SR and the ACK/NACK aretransmitted simultaneously, they may be arranged in order of theACK/NACK and the SR. When the SR and the CSI are transmittedsimultaneously, they may be arranged in order of the CSI and the SR.When the SR, the CSI, and the ACK/NACK are transmitted simultaneously,they may be arranged in order of the CSI, the ACK/NACK, and the SR.

III. Classification of Transmission Resource Based on UCI TransmissionCombination.

As described above, if the same format (e.g., the PUCCH format 3) andthe same resource are used in a case where ACK/NACK (SR may also beincluded) and CSI are transmitted through multiplexing and a case whereonly the CSI is transmitted, ambiguity may occur according to apresence/absence of the ACK/NACK. In order to solve such ambiguity, amethod of first arranging UCI having no ambiguity in itspresence/absence as described above has a problem in that a codingscheme must be determined by securing a resource for UCI not transmittedin practice, and a result may occur in which information such as CSIhaving no ambiguity but having less importance is coded with an RM basissequence having a low BSI.

Therefore, the present invention proposes a method for performingtransmission using different formats for a case of transmitting ACK/NACKand CSI through multiplexing and a case of transmitting only the CSI, oreven if the same format is used, for performing transmission byallocating resources distinguished mutually exclusively.

For example, when a UL subframe in which a UE transmits CSI is asubframe n, in a DL subframe (i.e., subframe n-k) corresponding to thesubframe n, the following is achieved.

i) When a DL channel which requires an ACK/NACK response cannot bedetected and thus only the CSI is transmitted in the UL subframe, UCIconsisting of only the CSI is configured and a 1^(st) resource is used.

ii) When the DL channel which requires the ACK/NACK response is detectedand thus the ACK/NACK and the CSI are transmitted together throughmultiplexing in the UL subframe, UCI consisting of ACK/NACK+CSI isconfigured and a 2^(nd) resource is used.

The following description is about the 1^(st) resource and the 2^(nd)resource.

FIG. 20 is an example of a 1^(st) resource and a 2^(nd) resource.

The 1^(st) resource and the 2^(nd) resource imply resources or formatsdistinguished in a mutually exclusive manner.

The 1^(st) resource may use one fixed resource pre-assigned by RRC. Inaddition, the 2^(nd) resource may be used by selecting one resource,which is indicated by an ARI, from a plurality of resource (e.g., 4resources) pre-assigned by RRC, that is, from a resource set. The ARI istransmitted through a DL channel which requires ACK/NACK, e.g., an SPSrelease PDCCH or a control channel (PDCCH) for scheduling a PDSCH whichrequires ACK/NACK.

FIG. 21 shows an example of a resource selection method when ACK/NACKand CSI can be transmitted through multiplexing by using the sameformat.

As to a UL subframe for transmitting periodic CSI, a UE determineswhether a DL channel which requests an ACK/NACK response is detected ina DL subframe corresponding to the UL subframe (step S110).

If the DL channel is not detected, the UE configures UCI by using onlythe periodic CSI (step S140), and transmits the UCI through one fixed1^(st) resource pre-assigned by RRC (step S150). On the other hand, ifthe DL channel is detected, the UE configures UCI consisting of periodicCSI and ACK/NACK for the DL channel (step S120), and transmits the UCIthrough a 2^(nd) resource indicated by an ARI among a plurality ofresources assigned by RRC.

In FIG. 21, the 1^(st) resource or the 2^(nd) resource is selectedaccording to whether the DL channel is detected. More specifically, the1^(st) resource or the 2^(nd) resource may be selected according towhether the UE receives the ARI in the DL channel. For example, a PUCCHformat 3 is set to the UE for ACK/NACK transmission, and a UL subframein which ACK/NACK transmission is set together with periodic CSI isassumed. If the PUCCH format 3 resource (i.e., 2^(nd) resource) isindicated by an ARI in a DL channel which requests ACK/NACK or a PDCCHfor scheduling this, the UE multiplexes ACK/NACK (SR may be included)and periodic CSI for one cell by joint-coding them up to 22 bits, andtransmits them through the PUCCH format 3 resource (i.e., 2^(nd)resource) indicated by the ARI. On the other hand, if the ARI is notpresent, UCI consisting of only periodic CSI is transmitted through the1^(st) resource pre-assigned by RRC.

That is, when the method of FIG. 21 is used, the UE may operate asfollows. The UE receives a data unit which requests an ACK/NACK responsein a downlink subframe. Herein, the data unit may be a codewordtransmitted through a physical downlink shared channel (PDSCH) of thedownlink subframe or a PDCCH or the like transmitted in the downlinksubframe. The PDCCH may be a PDCCH indicating a release ofsemi-persistent scheduling (SPS). The UE transmits ACK/NACK for the dataunit in an uplink subframe. If the uplink subframe is configured totransmit periodic channel state information (CSI), the periodic CSI andthe ACK/NACK are transmitted through a physical uplink control channel(PUCCH) of the uplink subframe. The ACK/NACK and the periodic CSI may betransmitted through joint-coding. In this case, if an ACK/NACK resourceindicator (ARI) is included in the downlink subframe, a resource fortransmitting the PUCCH may be a plurality of resources pre-assigned by ahigher layer signal such as RRC, that is, one resource indicated by theARI in a resource set. The ARI may be included in downlink controlinformation (DCI) transmitted through a physical downlink controlchannel (PDCCH) of the downlink subframe.

UL subframes in which periodic CSI can be transmitted may bepredetermined by a higher layer signal.

In addition, a PUCCH format in which the ACK/NACK is transmitted may bea PUCCH format pre-assigned by a higher layer signal as one of aplurality of PUCCH formats, for example, the aforementioned PUCCH format3. The PUCCH format 3 is a PUCCH format capable of transmittinginformation bit of up to 22 bits.

In addition, if a PUCCH resource used when only periodic CSI istransmitted in the uplink subframe is a 1^(st) resource and one resourceindicated by the ARI is a 2^(nd) resource, the 1^(st) resource and the2^(nd) resource are resources distinguished in a mutually exclusivemanner as described above with reference to FIG. 20.

According to the aforementioned method, since mutually distinguishedresources are used in a case of transmitting the ACK/NACK and theperiodic CSI together and a case of transmitting only the periodic CSI,ambiguity does not occur from a perspective of a BS. Therefore, UCI canbe transmitted in a reliable and effective manner. Meanwhile, in amethod of allocating the 1^(st) resource and the 2^(nd) resource,according to a CC which is a target of ACK/NACK and/or the number ofACK/NACK bits or according to whether an ARI is obtained, the followingresource allocation method can be configured.

1) When ACK/NACK for a ‘combination of 1^(st) ACK/NACK targets’ (called‘ACK/NACK combination 1’) and CSI must be transmitted together or whenonly the CSI is transmitted without an ACK/NACK transmission target, a1^(st) resource is used by configuring UCI consisting of the ACK/NACKcombination 1 and the CSI.

2) When ACK/NACK for a ‘combination of 2^(nd) ACK/NACK targets’ (called‘ACK/NACK combination 2’) and CSI must be transmitted together, a 2^(nd)resource is used by configuring UCI consisting of the ACK/NACKcombination 2 and the CSI.

FIG. 22 shows an example of a UCI configuration in a 1^(st) resource anda 2^(nd) resource.

Referring to FIG. 22, the 2^(nd) resource is a case where ACK/NACK andperiodic CSI are transmitted together, and the ACK/NACK and the periodicCSI are arranged. The 1^(st) resource secures a resource for an ACK/NACKcombination 1 even if a combination of the 1^(st) ACK/NACK target cannotbe detected and thus only CSI is generated. This is to prepare asituation in which ambiguity occurs between a BS and a UE when the BStransmits a DL channel which requires an ACK/NACK response but the UEfails to detect to this. This method is similar to a method of securingan ACK/NACK resource always irrespective of whether an actual ACK/NACKresponse target channel is detected, but has an advantage in that aresource waste can be decreased in a sense that the ACK/NACK combination1 secures only an ACK/NACK resource for basic communication between theBS and the UE.

For example, in case of FDD, if a DL transmission mode of a PCC is asingle-codeword transmission mode, one bit may be secured, and if the DLtransmission of the PCC is a multi-codeword transmission mode, two bitsmay be secured, so as to be used in case of PCC scheduling. In case ofTDD, one bit (single-codeword transmission mode) or two bits(multi-codeword transmission mode) may be used as an ACK/NACK responsefor one channel transmitted through the PCC in one UL subframe, ortransmission may be performed by securing two bits as an ACK/NACKresource for a plurality of channels transmitted through the PCC. Inaddition, in an SR subframe, an SR bit field may also be included in the‘ACK/NACK combination 1’.

In a bit ACK/NACK position, an ACK/NACK bundling (e.g., spatial bundlingand/or a logical AND operation, a consecutive ACK counter, etc.) schememay be applied for compression transmission.

In case of TDD, by considering a case where an ACK/NACK for “‘PDCCH(e.g., SPS release) with downlink assignment index (DAI)=1 andrequesting an ACK/NACK response’ or ‘DAI=1 of the PDCCH when a PDSCHscheduled with a PDCCH exists only one in a PCC’” is generatedsimultaneously with an ACK/NACK for an “(SPS) PDSCH scheduled without aPDCCH”, transmission may be performed by securing two bits or more totransmit each ACK/NACK. For example, in the multi-codeword transmissionmode, three bits may be secured so that a first bit is used as a PDSCHscheduled without a PDCCH and the remaining two bits are used as ‘PDSCHwith DAI=1’ or ACK/NACK for an SPS release PDCCH with DAI=1. In thesingle-codeword transmission mode, two bits may be secured so that onebit is used as a ‘PDSCH scheduled without a PDCCH’ and the remaining onebit is used as a PDSCH with DAI=1 or ACK/NACK for an SPS release PDCCHwith DAI=1.

An ACK/NACK bit may be mapped to a bit order predetermined according toa condition of an ACK/NACK target as described in the above example. Forexample, an ACK/NACK bit for the ‘PDSCH scheduled with the PDCCH’ ismapped from an MSB side of the ‘ACK/NACK combination 1’, and if anACK/NACK bit for the ‘PDSCH scheduled without the PDCCH’ is included, ismapped to an LSB side of the ‘ACK/NACK combination 1’. In addition, inan SR subframe, if an SR bit field is included in the ‘ACK/NACKcombination 1’, it may be mapped to an LSB of the ‘ACK/NACK combination1’.

In particular, in the above description, if the 1^(st) resource and the2^(nd) resource use the same PUCCH format (e.g., PUCCH format 3) intransmission, a resource of the ‘ACK/NACK combination 1’ may be securedfor the 1^(st) resource.

Meanwhile, the number of ACK/NACK bits of the ACK/NACK combination 2 isthe maximum number of ACK/NACK bits that can be generated in a ULsubframe and is determined according to the number of DL CCs assigned tothe UE and a transmission mode of each DL CC, and in case of TDD, isdetermined by additionally considering the number of DL subframescorresponding to one UL subframe.

The 1^(st) ACK/NACK target combination and the 2^(nd) ACK/NACK targetcombination may be determined as follows.

A target of ACK/NACK which cannot obtain an ARI since ACK/NACKtransmission is required and a PDCCH including the ARI does not exist isa 1^(st) ACK/NACK target combination. A target of ACK/NACK whichrequires ACK/NACK transmission and which can obtain the ARI since thePDCCH including the ARI exists is a 2^(nd) ACK/NACK target combination.

A resource allocation method based on an ACK/NACK target CC and/or thenumber of ACK/NACK bits is as follows.

If it is configured to use a PUCCH format 3 for ACK/NACK transmissionfor multiple CCs in FDD or if it is configured to use channel selectionof PUCCH formats 1a/1b for ACK/NACK transmission for multiple CCs,ACK/NACK transmission is required in a UL subframe for transmitting CSI,and if the following cases are satisfied in a DL subframe correspondingto the UL subframe, it is the 1^(st) ACK/NACK target combination.

i) When one PDSCH exists only in a PCC and is scheduled without a PDCCH.

ii) When one PDSCH exists only in the PCC and is scheduled through thePDCCH.

iii) When one PDCCH exists only in the PCC and the PDCCH requires anACK/NACK response.

In other cases, it is the 2^(nd) ACK/NACK target combination.

If it is configured to use a PUCCH format 3 for ACK/NACK transmissionfor multiple CCs in TDD or if it is configured to select a PUCCH format1a/1b channel for ACK/NACK transmission for multiple CCs, a UL subframe(i.e., subframe n) for transmitting CSI for a DL CC requires ACK/NACKtransmission, and the following cases may exist in a DL subframe (i.e.,subframe n-k, where k is an element of a set K, and K is a setconsisting of M elements and defined by 3GPP TS 36.213 V10, EvolvedUniversal Terrestrial Radio Access (E-UTRA); Physical layer procedures(Release 10) table 10.1.3.1-3) corresponding to this UL subframe.

i) When there is only one PDSCH scheduled without a PDCCH in a PCC aloneand there is no PDCCH which requires an ACK/NACK response.

ii) When there is only one PDSCH scheduled with a PDCCH in a PCC aloneand there is a PDCCH with DAI=1.

iii) When there is only one PDCCH with DAI=1 which requires an ACK/NACKresponse and there is no PDSCH.

iv) When there is a PDCCH with DAI=1 which requires an ACK/NACK responseor there is only one PDSCH scheduled with a PDCCH in a PCC alone andthere is only one PDSCH with DAI-1 of the PDCCH and scheduled without aPDCCH at the same time.

In the above cases i to iv), it is the 1^(st) ACK/NACK targetcombination.

In other cases, it is the 2^(nd) ACK/NACK target combination.

If it is configured to select a PUCCH format 1a/1b channel for ACK/NACKtransmission for multiple CCs in TDD, a UL subframe (i.e., subframe n)which transmits CSI for a DL CC requires ACK/NACK transmission. If aPDSCH or a PDCCH which requires an ACK/NACK response is received only ina PCC in a DL subframe (i.e., subframe n-k) corresponding to this ULsubframe, it is the 1^(st) ACK/NACK target combination, and otherwise,it is the 2^(nd) ACK/NACK target combination.

IV. Method of Indicating CSI Transmission Resource.

Periodic CSI transmission is achieved according to a period configuredin advance by RRC, and does not have a related PDCCH. Therefore, alocation of a resource for CSI transmission is predetermined.

Meanwhile, in ACK/NACK transmission, a PDCCH for scheduling a PDSCHexists, and an ACK/NACK resource indicator (ARI) included in the PDCCHis used to indicate a location of an ACK/NACK transmission resource.Since an ARI bit is limited, a resource that can be indicated islimited. Therefore, a resource set is assigned in advance by RRC, and anARI in the resource set is used to indicate a specific resource. Forexample, since four resources can be indicated if the ARI bit is 2 bits,a resource set including the four resources can be assigned by RRC, andthe ARI can be used to indicate any one of the four resources.

If a CSI resource and an ACK/NACK resource are assigned independently,five resources are assigned by RRC. If the CSI resource and the ACK/NACKresource have the same format, in order to decrease an unnecessaryresource assignment, the CSI resource can be used as one of ACK/NACKresource sets designated by RRC. That is, a resource set for ACK/NACKmay be assigned by RRC, and thereafter a resource for CSI may beindicated by using an ARI, or the resource for CSI may use a resource ofa predetermined ARI without an indication of the ARI through a PDCCH.For example, a resource indicated by a value of ARI=0 may be fixed inadvance to be used as a resource for CSI. The resource for ACK/NACK maybe limited to a resource indicated by a value of ARI=1, 2, 3 todistinguish it from the resource for CSI.

In a UL subframe scheduled to transmit CSI and ACK/NACK simultaneously,only the CSI is transmitted using a resource for CSI. In an ACK/NACKresource, the ACK/NACK and the CSI may be transmitted together.

Alternatively, the resource for CSI may have a form in which an ACK/NACKcombination for a certain specific target is included, and the ACK/NACKresource may have a form in which an ACK/NACK combination 2 and the CSIare transmitted simultaneously.

Meanwhile, in the conventional ARI transmission, in case of FDD,transmission is performed by using a TPC field of a PDCCH for schedulinga PDSCH of a secondary cell. A TPC field of a PDCCH for scheduling aPDSCH of a primary cell is used for a power control usage which is anoriginal usage. In case of TDD, transmission is performed by using a TPCfield of the remaining PDCCHs other than a PDCCH (a TPC field of thisPDCCH is used for a power control usage which is an original usage) forscheduling a PDSCH of a primary cell while having a DAI initial value(e.g., 1). If the CSI and the ACK/NACK are transmitted throughmultiplexing, a format and resource reserved for RRC may be used for CSItransmission. In this case, an indication of an ARI for designating anACK/NACK transmission resource is unnecessary. Therefore, a bit used forthe ARI may be used as follows.

1) TPC as Original Usage

All TPC values are signaled with the same value. In a case where acorresponding TPC value is used as a final power value or in case ofFDD, an independent TPC value per CC may be signaled and an accumulationsum may be used as the final power value. Alternatively, in case of TDD,as to the same subframe, the same TPC value may be signaled for all CCsand a corresponding TPC value is independent for each subframe, and anaccumulation sum of a corresponding TPC value for each subframe may beused as a final power Value.

2) Used for Indicating UCI Combination

For example, a restriction of the maximum number of payload bits thatcan be transmitted or a limitation of a transmit power/code rate for arequested SINR may be considered to indicate a UCI combination asfollows.

When there is periodic CSI for a plurality of DL CCs, a specific DL CCfor which the periodic CSI is transmitted may be indicated. For example,all DL CCs, a predetermined DL CC or a specific DL CC may be directlyindicated. On the other hand, a DL CC for dropping CSI may be indicated.

Alternatively, what will be transmitted by using the CSI may beindicated. For example, it may be indicated to transmit all of PMI, RI,and CQI, or a specific content (RI, PTI) having a priority may beindicated, or a specific content may be directly indicated.Alternatively, CSI to be dropped, not be transmitted, may be indicated.Information regarding whether CSI information is compressed (i.e., apredetermined simplified CSI information combination is used) may beindicated.

The indicated Information may be in regards to the maximum number ofACK/NACK payload bits that can be transmitted (or indirect informationcapable of measuring this, e.g., an ordinal value or the number of CCsscheduled in a downlink time duration corresponding to an uplinksubframe, an ordinal value or the number of subframes), whether anACK/NACK bit is compressed (whether spatial bundling is used, whether anadditional subframe/CC region bundling, etc., is applied), etc.

A method of configuring a format in a designated resource may beindicated. For example, if a PUCCH format 3 is used, a capacity may becontrolled by controlling a spreading factor value. Alternatively,information regarding the total number of bits that can be transmittedmay be indicated.

Alternatively, if a transmission resource only for CSI is configured touse an ACK/NACK resource corresponding to a specific ARI value, the ARImay indicate the specific ARI value as a virtual CRC usage.

V. Coding Scheme

In case of using a PUCCH format 3, a selection criterion of single RMand double RM is required. For this, the single RM may be used when thenumber of bits of UCI is less than or equal to 11 bits, and the doubleRM may be used when the number of bits of UCI is greater than 11 bits.Of course, this is for exemplary purposes only.

1. Method of Determining Based on the Total Number of Bits of UCICombination Actually Transmitted by UE.

ACK/NACK is transmitted based on the number of ACK/NACK bits, and CSI istransmitted based on the total number of CSI bits. When the ACK/NACK andthe CSI are transmitted simultaneously, transmission is performed basedon the number of ACK/NACK bits and the number of CSI bits.

When the ACK/NACK and the SR are transmitted simultaneously,transmission is performed based on the total sum of the number ofACK/NACK bits and the number of SR bits. When the SR and the CSI aretransmitted simultaneously, transmission is performed based on the totalsum of the number of SR bits and the number of CSI bits. When theACK/NACK, the SR, and the CSI are transmitted simultaneously,transmission is performed based on the total sum of the number ofACK/NACK bits, the number of SR bits, and the number of CSI bits.

2. Method Based on the Total Sum of Transmissible UCI Combination HavingAmbiguity and UCI Combination Having No Ambiguity.

Even in a case where a UE must transmit ACK/NACK in practice but missesit, the same coding scheme is maintained irrespective of whether anerror occurs, so that a field configuration has no error when a BSdecodes UCI and additional blinding decoding is not caused.

ACK/NACK transmission is performed based on the number of ACK/NACK bits,and CSI transmission is performed based on the total sum of the numberof CSI bits and the number of transmissible ACK/NACK bits. Preferably,NACK is transmitted in a bit position for ACK/NACK.

The ACK/NACK and the CSI are transmitted simultaneously based on thenumber of ACK/NACK bits and the number of CSI bits. The ACK/NACK and theSR are transmitted simultaneously based on the total sum of the numberof ACK/NACK bits and the number of SR bits. The SR and the CSI aretransmitted simultaneously based on the total sum of the number of SRbits, the number of CSI bits, and the number of transmissible ACK/NACKbits. Preferably, NACK is transmitted in a bit position for ACK/NACK.

The ACK/NACK, the SR, and the CSI are transmitted simultaneously basedon the total sum of the number of ACK/NACK bits, the number of SR bits,and the number of CSI bits.

3. Method Based on the Total Sum of Transmissible UCI Combination HavingAmbiguity and UCI Combination Having No Ambiguity.

This is a method based on the total sum of all combinations, that is,the number of ACK/NACK bits, the number of SR bits, and the number ofCSI bits.

The number of transmissible ACK/NACK bits is determined by the number ofACK/NACK bits that can be generated in a corresponding subframe. It isdetermined by the number of DL CCs assigned to a UE and a downlinktransmission mode in each DL CC (according thereto, the maximum numberof transmission blocks that can be scheduled in one downlink subframe isdetermined). In case of TDD, the number of DL subframes corresponding toone UL subframe must also be taken into account.

If a DL channel combination which is an ACK/NACK target is distinguishedsuch as the ACK/NACK combination 1 and the ACK/NACK combination 2 andthe number of ACK/NACK bits is determined according thereto, the numberof transmissible ACK/NACK bits may be the number of bits based on theACK/NACK combination 1 and the ACK/NACK combination 2.

VI. Individual Coding of ACK/NACK, SR, and CSI

An individual coding method is proposed when ACK/NACK (an SR bit may beadded to ACK/NACK in a subframe in which SR is transmitted, hereinafterthe same shall apply) and CSI are multiplexed.

FIG. 23 is an example of individual coding of ACK/NACK and CSI.

Referring to FIG. 23, mapping is performed to an RM coding block foreach UCI type. Given that an error may occur in a presence/absence ofACK/NACK, it may be considered that CSI is mapped in a fixed manner onlyto a segment in a CSI transmission subframe irrespective of thepresence/absence of ACK/NACK. The remaining segments are used forACK/NACK transmission.

In a UL subframe in which a UE does not transmit CSI, ACK/NACK may betransmitted using all resources in a PUCCH format 3 assigned to the UE.On the other hand, even if the UE does not have ACK/NACK to betransmitted in the UL subframe, the CSI is mapped to the remainingresource other than a resource to which maximum ACK/NACK informationthat can be generated in a corresponding configuration is mapped.

Independent coding is applied to the ACK/NACK and the CSI, and may beRM-coded by mapping to each part of double RM coding. Rate matching maybe applied differently according to a performance requirement for eachof the ACK/NACK and the CSI.

That is, although an output of a double RM encoder is alwaysrate-matched with 24 bits in the conventional PUCCH format 3, accordingto the number of CSI and ACK/NACK bits mapped to each RM and thecapability requirement, a coded output of each RM is rate-matched withmore than 24 bits (i.e., more than 12 QPSK modulation symbols) or lessthan 24 bits (i.e., less than 12 QPSK modulation symbols), and a sum ofthe number of coded bits of two RM coding outputs is 48 (i.e., 24 QPSKmodulation symbols). In general, a capability requirement of ACK/NACK isless than BER 10⁻³, and a capability requirement of CSI is less thanBLER 10⁻2.

Meanwhile, UCI may be grouped according to a priority of information anda requirement for an error rate. Information in a group may bejoint-coded, and separate coding may be performed between groups.

As an example of grouping, ACK/NACK and SR may be determined to a 1^(st)group, and CSI may be determined to a 2^(nd) group. Alternatively, amonga plurality of pieces of information of CSI, information (e.g., RI, PTI,W1, etc.) having an effect on information to be delivered in nexttransmission is included in the 1^(st) group which is the same group asthe ACK/NACK, by giving a priority similar to that of the ACK/NACK, andthe other information (e.g., CQI, PMI, etc.) may be included in the2^(nd) group. When only the 1^(st) group (or 2^(nd) group) istransmitted, the 1^(st) group is joint-coded with single RM or doubleRM. When the 1^(st) group and the 2^(nd) group are transmittedsimultaneously, the 1^(st) group and the 2^(nd) group may beindividually coded to 1^(st) RM coding of double RM and 2^(nd) RM codingof double RM, respectively. According to an information amount, a codingscheme other than RM may be applied to UCI.

FIG. 24 is an example of a coding scheme of UCI.

Referring to FIG. 24, UCI may be selectively coded to any one of singleRM, double RM, and tail biting convolution coding (TB CC) according to abit amount. For example, in case of ACK/NACK, single RM is used up to 10bits (if an SR is included, 11 bits). Regarding CSI, CSI for a pluralityof DL CCs may be applied, thereby applying double RM (regarding the CSIfor the plurality of DL CCs, independent coding may be applied for eachDL CC). Rate matching may vary for a coded bit in which CSI and ACK/NACKinformation is channel-coded according to an error rate requested perinformation. When repetition coding, simplex coding, etc., are selectedas a coding scheme, the repetition coding may be applied to one bit, andthe simplex coding may be applied to 2-bit ACK/NACK.

To prevent the coding scheme from changing depending on a UCIinformation amount, a method of limiting an input bit of each RM to beless than 11 bits may be considered. That is, the input bit is limitednot to exceed 11 bits for each of the 1^(st) group and the 2^(nd) group.For this, UCI of each group can perform bundling if ACK/NACK exceeds 10bits (if an SR is included, 11 bits). CSI may be dropped when exceeding11 bits. If ACK/NACK, SR, RI, PTI, and W1 are grouped, they are groupedinto one group only when the total sum is less than or equal to 11 bits.If ACK/NACK and SR are grouped and a sum of other information to betransmitted simultaneously exceeds 11 bits, only ACK/NACK and SR may betransmitted as the 1^(st) group, and the other information may betransmitted by being grouped into the 2^(nd) group.

VII. Content Indicator Transmission

As described above, ambiguity may occur for a presence/absence ofACK/NACK. One method of solving this is to reserve (prepare) a specificbit field irrespective of the presence/absence of ACK/NACK. However,such a method has a disadvantage in that a resource efficiencydeteriorates.

In the present invention, if UCI is transmitted in combination, anindicator for announcing a transmission UCI content combination may beincluded in a field in a specific fixed location.

FIG. 25 shows an example of including a UCI content indicator.

As shown in FIG. 25, one bit among UCI bits may indicate whether toinclude a specific UCI type, e.g., ACK/NACK. For example, the UCIcontent indicator may indicate whether an ‘ACK/NACK combination 1’ isincluded in a 1^(st) resource by referring to FIG. 22.

Alternatively, a UCI combination may be reported with a plurality ofbits. In this case, it may be reported by including the number of CSItransmission target DL CCs, the number of ACK/NACK bits, whether toselect CSI or ACK/NACK, etc.

The UCI content indicator may be individually coded by distinguishing itfrom other UCIs to improve a decoding performance. Additional channelcoding may be performed when combining with other UCIs. That is, 1^(st)channel coding may be performed first on the UCI content indicator, andthereafter 2^(nd) channel coding may be performed together with otherUCIs. For example, repetition coding may be performed on a 1-bit UCIcontent indicator, and simplex coding may be performed on a 2-bit UCIcontent indicator, and thereafter joint coding may be performed togetherwith other UCIs.

A UCI combination may be regulated according to the number of availablebits of a UL control channel on the basis of whether ACK/NACKtransmission is performed. That is, only ACK/NACK may be transmitted byutilizing all resources while dropping CSI in a UL subframe in which theCSI is transmitted, or compressed ACK/NACK and CSI for one DL CC may betransmitted, or CSI transmission for a plurality of DL CCs withoutACK/NACK transmission may be indicated.

A method of using a UCI content indicator and a method described withreference to FIG. 22 may be selectively used.

For example, a PUCCH format 3 may be assigned through RRC for thepurpose of transmitting UCI consisting of only CSI to a UE.

In this case, i) some of resources for transmitting the PUCCH format 3are reserved for ACK/NACK (i.e., an ACK/NACK combination 1). This is toprepare for a case where the UE misses a data unit which requestsACK/NACK, i.e., a combination of an ACK/NACK target. A resource preparedfor ACK/NACK may be: 1) 1 or 2 bits according to the number ofcodewords; 2) in case of TDD, may be added with a 1-bit ACK/NACK bit forSPS PDSCH other than bits of the case 1); and 3) an SR bit may also beincluded in an SR subframe. This is a method described with reference toFIG. 22.

Alternatively, in the above case, ii) the UE may use a UCI contentindicator to report whether the ACK/NACK combination 1 is included.

That is, the above method i) is a method in which some resources of thePUCCH format 3 for UCI configured only with CSI are reserved forACK/NACK, and the method ii) is a method of reporting a combination ofUCI by transmitting a UCI content indicator to some resources of thePUCCH format 3 for UCI configured only with CSI.

VIII. Selection of Transmission Resource Based on UCI Combination whenSimultaneous Transmission of ACK/NACK and CSI is Configured.

When it is configured to simultaneously transmit multiple ACK/NACK andCSI through multiplexing, a UE may select a transmission resourceaccording to a UCI combination to be transmitted.

In ACK/NACK transmission, PUCCH formats 1a/1b are used when there is oneSPS PDSCH transmitted through a PCC, or when there is one PDSCHtransmitted through a PCC scheduled with a PDCCH, or when there is onePDCCH (e.g., SPS release PDCCH) requesting an ACK/NACK response. Channelselection of PUCCH formats 1a/1b is used when one SPS PDSCH transmittedthrough a PCC coexists with a PDSCH transmitted through a PCC scheduledwith a PDCCH or a PDCCH (SPS release PDCCH) requesting an ACK/NACKresponse. In other cases, the PUCCH format 3 is used. ACK/NACK may betransmitted up to 20 bits.

In CSI transmission, when only CSI for one CC is transmitted withoutACK/NACK, the CSI is transmitted with the PUCCH format 2. When aplurality of CSIs must be transmitted, the PUCCH format 3 is used.

In a case where ACK/NACK and CSI are transmitted simultaneously, whenthere is one SPS PDSCH transmitted through a PCC, or when there is onePDSCH transmitted through a PCC scheduled with a PDCCH, or in a casewhere there is one PDCCH requesting an ACK/NACK response and only CSIfor one CC is transmitted, the CSI is transmitted with the PUCCH format2. ACK/NACK is transmitted through reference signal modulation of thePUCCH format 2. In other cases, transmission is performed bymultiplexing with the PUCCH format 3. For CSI multiplexing, ACK/NACK maybe compressed by using bundling, a counter, etc.

When there is one SPS PDSCH transmitted through a PCC in a subframe inwhich CSI for a plurality of DL CCs collides, or when there is one PDSCHtransmitted through a PCC scheduled with a PDCCH, or in a case wherethere is one PDCCH requesting an ACK/NACK response, only CSI for one DLCC may be selected for a fallback operation while dropping the remainingCSIs. The selected CSI may be transmitted with the PUCCH format 2, andthe ACK/NACK may be transmitted through reference signal modulation ofthe PUCCH format 2.

In simultaneous transmission of the ACK/NACK and the SR, when there isone SPS PDSCH transmitted through a PCC or when there is one PDSCHtransmitted through a PCC scheduled with a PDCCH, or in a case wherethere is one PDCCH requesting an ACK/NACK response, a negative SR may betransmitted through a dynamic format 1a/1b resource (i.e., a resourcecorresponding to a 1^(st) CCE in which a PDCCH is transmitted) orthrough a PUCCH format 1a/1b resource designated to SPS. A positiveACK/NACK may be transmitted by using a PUCCH format 1a/1b resourcedesignated to SR. In other cases, transmission may be performed bymultiplexing with the PUCCH format 3.

When SR and CSI are transmitted simultaneously, transmission may beperformed by multiplexing with the PUCCH format 3. When ACK/NACK, SR,and CSR are transmitted simultaneously, transmission may be performed bymultiplexing with the PUCCH format 3.

As described above, an LTE-A system may use a PUCCH format 3 to transmitmultiple ACK/NACK. In this case, a transmissible information amount maybe limited according to a limitation of a channel coding codebook size(e.g., in case of the PUCCH format 3, up to 20 bits or 22 bits), alimitation of the number of ACK/NACK information bits depending on thenumber of UCI (SR and/or CSI) bits other than ACK/NACK transmittedthrough a physical channel, or an uplink channel state. Assume that theformer is Y bit (e.g., 20 or 22 bits) and the latter is X bit. Herein,according to the uplink channel state, the X bit may be configured byRRC or may be signaled through a PDCCH.

Since ACK/NACK can be transmitted independently one-by-one per codeword,if the number of codewords in a DL subframe corresponding to one ULsubframe exceeds X, codewords may be grouped and ACK/NACK may betransmitted through bundling with respect to a corresponding group. Inthis case, the following rules can be applied.

Method 1. A method in which, if the number of codewords exceeds X,spatial bundling is first applied, and time-domain bundling or CC-domainbundling is applied between neighboring subframes.

1) If the number of codewords exceeds X, the codewords in the samesubframe performs bundling on ACK/NACK first. That is, spatial bundlingis performed.

2) If the number of ACK/NACK bits exceeds X even after spatial bundling,time-domain bundling is additionally applied. The time-domain bundlingis performed until the number of ACK/NACK bits becomes less than orequal to X bits according to a predetermined rule. For example, thepredetermined rule may be grouping from a first or last subframe.

3) If the number of ACK/NACK bits exceeds X bits even after thetime-domain bundling, neighboring subframe groups are additionallysubjected to time-domain bundling. The time-domain bundling is performeduntil the number of ACK/NACK bits becomes the X bit according to apredetermined rule. For example, the predetermined rule may be groupingfrom a first or last subframe.

Method 2. Method in which, if the number of codewords exceeds X, spatialbundling is first applied, and bundling based on a bundling mask isapplied.

1) If the number of codewords exceeds X, spatial bundling is firstapplied.

2) If the number of ACK/NACK bits exceeds X even after spatial bundling,bundling based on a bundling mask signaled with RRC is performed. Thebundling mask is information indicating a bundling group. The bundlinggroup may be defined in a CC domain or a time domain.

Method 3. Method in which bundling is configured such that the number ofcodewords does not exceeds X.

Instead of signaling a value X due to a limitation of the value X,whether to apply bundling may be directly configured. In this case, abundling unit may be any one of the followings.

Whether to apply spatial bundling may be configured commonly to allsubframes with respect to all CCs, or whether to apply spatial bundlingmay be configured in one subframe unit in one CC, whether to applyspatial bundling may be configured commonly to all subframes in the sameCC, whether to apply spatial bundling may be configured commonly to allCCs of the same subframe, or whether to apply spatial bundling may beconfigured commonly to all subframes having the same DL DAI value.

X may vary depending on M, i.e., the number of DL subframescorresponding to one UL subframe. For example, in TDD, M=2 and M=1coexist in a DL-UL configuration #1. M=3 and M=2 coexist in a DL-ULconfiguration #3 (the DL-UL configuration #1 and 3 may refer to 3GPP TS36.211 V10.2.0 (2011-06) table 4.2-2). In this case, the number ofcodewords for transmitting ACK/NACK may vary depending on the value M.Therefore, whether to apply spatial bundling may be configureddifferently according to the value M. For example, if M=3, when a CC towhich spatial bundling is applied is M=2, spatial bundling may not beapplied.

Alternatively, if M=2, a spatial bundling configuration may be applied,and if M=1, the spatial bundling configuration is not always applied andACK/NACK may be transmitted individually. Apparently, in an ACK/NACKtransmission format, a bundling configuration greater than or equal to Ybits that cannot be supported physically is excluded.

A UE may aggregate and use CCs configured with different TDD DL-ULconfigurations. In this case, according to a UL subframe in whichACK/NACK is transmitted, the number of DL subframes corresponding to theUL subframe may vary for each CC. Therefore, the number of codewordswhich must feed back ACK/NACK may change. Therefore, in this case, aspatial bundling configuration may differ for each UL subframe (of aprimary cell). Alternatively, the spatial bundling configuration maydiffer for each number of all codewords of a DL subframe of a primarycell and a DL subframe of a secondary cell corresponding to a ULsubframe. In addition, according to whether it is a CSI subframeconfigured to transmit CSI or according to the number of CSI bits, thespatial bundling configuration may differ.

In addition, as to a configuration for each UL subframe, a pattern ofone frame unit may be configured by considering a repetition period of achange in the number of codewords (e.g., it is generated by HARQ timingin TDD which uses a different DL-UL configuration for each cell), a CSItransmission period, etc., or a pattern of a plurality of frame unitsmay be configured.

In another method, in TDD which uses a different DL-UL configuration foreach cell, it may be considered to perform spatial bundling always forall CCs to simplify an A/N feedback configuration.

In another method, when multiple ACK/NACK and CSI are configured to betransmitted simultaneously, it may be configured such that spatialbundling is always applied.

In another method, if multiple ACK/NACK spatial bundling is applied to aUE due to a shortage of SINR, it may also be considered that the UE isnot allowed to simultaneously transmit multiple ACK/NACK and CSI byusing a PUCCH through multiplexing. In this case, ACK/NACK may belimited to an ACK/NACK combination in the presence of an ARI. That is,in case of an ACK/NACK combination in the presence of the ARI,simultaneous transmission of ACK/NACK and CSI is not allowed, and incase of an ACK/NACK combination in the absence of the ARI, simultaneoustransmission with CSI is allowed.

Additional bundling may be applied other than the spatial bundling. Theadditional bundling also applies differently according to a value M andthe number of respective codewords corresponding to one UL subframe.

A per-CC spatial bundling configuration may equally apply also to a casewhere ACK/NACK is piggybacked through a PUSCH. That is, the ACK/NACKwhich is piggybacked through the PUSCH has a UL grant for scheduling thePUSCH, and according to a UL DAI transmitted thereon, an ACK/NACKpayload size may vary adaptively depending on a DL PDSCH actuallyscheduled. The per-CC spatial bundling configuration may be directlyapplied to simplify an operation of a UE.

To allow ACK/NACK spatial bundling to be flexible, whether to performACK/NACK spatial bundling when transmitted through a PUSCH may beconfigured additionally from whether to perform ACK/NACK spatialbundling when transmitted through a PUCCH. Whether to perform spatialbundling may be configured differently according to a value M and avalue UL DAI (or a combination of M and UL DAI).

As shown in the aforementioned methods 1 and 2, if spatial bundling isselectively applied according to a maximum transmissible ACK/NACKinformation amount X, it may be applied simultaneously in a time domainwith all CCs when applying the spatial bundling, or bundling may beapplied sequentially according to X. That is, spatial bundling may beapplied sequentially in a unit of one PDSCH so that the ACK/NACKinformation amount is X, or spatial bundling may be applied sequentiallyin a unit of the same CC or the same subframe or the same DL DAI so thatthe ACK/NACK information amount is less than or equal to X. Such amethod is not limited to the aforementioned methods 1 and 2.

An order of performing spatial bundling may be a predetermined order,i.e., CC order/subframe order/DAI order. That is, bundling may beperformed on one CC and thereafter bundling of a next CC may beperformed.

In this case, since there is a higher possibility that scheduling of aPDSCH occurs frequently through a specific CC, e.g., a PCC, than a casewhere all CCs are simultaneously scheduled, it is more advantageous interms of data transmission efficiency to maintain individual ACK/NACK ofcodewords transmitted through the CC. Therefore, spatial bundling isapplied to the PCC at the end.

If an index value of the PCC is 0, to apply spatial bundling at the end,the spatial bundling may be applied gradually from a CC having thegreatest index.

Alternatively, since a DAI value is scheduled in an ascending order, thespatial bundling may be applied gradually from a subframe having a greatDAI so that the spatial bundling is performed on a subframe having thesmallest DAI value at the end.

Alternatively, if spatial bundling is required, the spatial bundling maybe first applied to the entire SCC, and only when exceeding X bits, thespatial bundling may be applied to a PCC.

In the present invention, spatial bundling implies bundling performed onACK/NACK for a plurality of codewords received in one DL subframe in oneCC. For example, each ACK/NACK (i.e., 1 if ACK, and 0 if NACK, or viceversa) for two codewords are subjected to a logical AND operation toderive one piece of ACK/NACK information.

Bundling between CCs implies bundling of ACK/NACK for a plurality ofcodewords received from the same subframes of different CCs assigned toa UE. For example, assume that a DL CC 0 and a DL CC 1 are assigned tothe UE. A BS may transmit two codewords in a DL subframe N of the DL CC0, and may transmit one codeword in a DL subframe N of the DL CC 1. Inthis case, the UE may perform bundling on 3-bit ACK/NACK information forthe three codewords to generate 1-bit ACK/NACK information. That is,only when all of the three codewords are successfully received, ACK isgenerated, and otherwise, NACK is generated.

The bundling between CCs may be applied to all DL subframes, and may beapplied only some DL subframes according to a determined rule.

Bundling in a time domain implies bundling performed by the UE onACK/NACK for a data unit (PDSCH, or codeword) received in different DLsubframes. For example, assume that a DL CC 0 and a DL CC 1 are assignedto the UE, the DL CC 0 is a MIMO mode capable of receiving twocodewords, and the DL CC 1 is a single-codeword transmission modecapable of receiving one codeword. In this case, if the UE successfullyreceives a codeword 0 and a codeword 1 in a DL subframe 1 of the DL CC0, and successfully receives only a codeword 0 in a DL subframe 2 of theDL CC 1, the UE generates ACK as to the codeword 0, and generates NACKas to the codeword 1. That is, ACK/NACK bundling is performed for eachcodeword received in different DL subframes. In addition, it is alsopossible to count the number of consecutive ACK bits for each codewordreceived in different subframes. Herein, a subframe order may bedetermined according to a subframe index or a DAI.

FIG. 26 is a block diagram of a BS and a UE according to an embodimentof the present invention.

A BS 100 includes a processor 110, a memory 120, and a radio frequency(RF) unit 130. The processor 110 implements the proposed functions,procedures, and/or methods. Layers of a radio interface protocol can beimplemented by the processor 110. The processor 110 can configureperiodic CSI transmission and SR transmission through a higher layersignal such as an RRC message. For example, the processor 110 canannounce a subframe in which periodic CSI, SR, etc., can be transmitted.In addition, the processor 110 can configure a UE to use a PUCCH formatto be used in ACK/NACK feedback, for example, a PUCCH format 3. Thememory 120 is coupled to the processor 110, and stores a variety ofinformation for driving the processor 110. The RF unit 130 is coupled tothe processor 110, and transmits and/or receives a radio signal.

A UE 200 includes a processor 210, a memory 220, and a radio frequency(RF) unit 230. The processor 210 implements the proposed functions,procedures, and/or methods. Layers of a radio interface protocol may beimplemented by the processor 210. The processor 210 receives a data unitrequesting an acknowledgement/not-acknowledgement (ACK/NACK) response ina downlink subframe, and transmits ACK/NACK for the data unit in anuplink subframe. In this case, if the uplink subframe is configured totransmit channel state information (CSI), the periodic CSI and theACK/NACK are transmitted together through a physical uplink controlchannel (PUCCH) of the uplink subframe. In this case, if an ACK/NACKresource indicator (ARI) is included in the downlink subframe, aresource for transmitting the PUCCH is one resource indicated by the ARIamong a plurality of resources pre-assigned by a higher layer signal.The memory 220 is coupled to the processor 210, and stores a variety ofinformation for driving the processor 210. The RF unit 230 is coupled tothe processor 210, and transmits and/or receives a radio signal.

The processors 110 and 210 may include an application-specificintegrated circuit (ASIC), a separate chipset, a logic circuit, and/or adata processing unit. The memories 120 and 220 may include a read-onlymemory (ROM), a random access memory (RAM), a flash memory, a memorycard, a storage medium, and/or other equivalent storage devices. The RFunits 130 and 230 may include a base-band circuit for processing a radiosignal. When the embodiment of the present invention is implemented insoftware, the aforementioned methods can be implemented with a module(i.e., process, function, etc.) for performing the aforementionedfunctions. The module may be stored in the memories 120 and 220 and maybe performed by the processors 110 and 210. The memories 120 and 220 maybe located inside or outside the processors 110 and 210, and may becoupled to the processors 110 and 210 by using various well-known means.

1-10. (canceled)
 11. A method for receiving uplink control information(UCI), performed by a base station (BS) in a wireless communicationsystem, the method comprising: transmitting a data unit to a userequipment (UE) in a downlink subframe; and receivingacknowledgement/not-acknowledgement (ACK/NACK) for the data unit fromthe UE in an uplink subframe, wherein if the BS sets the UE tosimultaneously transmit periodic channel state information (CSI) and theACK/NACK, and if the BS indicates one resource for a physical uplinkcontrol channel (PUCCH) by a specific field included in downlink controlinformation (DCI) among a plurality of resources, the periodic CSI andthe ACK/NACK are received using the one resource for the PUCCH in theuplink subframe.
 12. The method of claim 11, wherein uplink subframes inwhich the periodic CSI can be transmitted by the UE are predetermined bythe BS.
 13. The method of claim 11, wherein a PUCCH format in which theACK/NACK is transmitted by the UE is predetermined to one of a pluralityof PUCCH formats by the BS.
 14. The method of claim 13, wherein up to 22information bits are received through the predetermined one of theplurality of PUCCH formats.
 15. The method of claim 11, wherein the DCIis transmitted through a physical downlink control channel (PDCCH) ofthe downlink subframe.
 16. The method of claim 11, wherein the data unitis a codeword transmitted through a physical downlink shared channel(PDSCH) of the downlink subframe or a PDCCH indicating a release ofsemi-persistent scheduling (SPS) transmitted in the downlink subframe.17. A base station (BS) for receiving uplink control information, the BScomprising: a transceiver for transmitting or receiving a radio signal;and a processor coupled to the transceiver, wherein the processor isconfigured to: transmit a data unit to a user equipment (UE) in adownlink subframe; and receive acknowledgement/not-acknowledgement(ACK/NACK) for the data unit from the UE in an uplink subframe, whereinif the BS sets the UE to simultaneously transmit periodic channel stateinformation (CSI) and the ACK/NACK, and if the BS indicates one resourcefor a physical uplink control channel (PUCCH) by a specific fieldincluded in downlink control information (DCI) among a plurality ofresources, the periodic CSI and the ACK/NACK are received using the oneresource for the PUCCH in the uplink subframe.
 18. The BS of claim 17,wherein uplink subframes in which the periodic CSI can be transmitted bythe UE are predetermined by the BS.
 19. The BS of claim 17, wherein aPUCCH format in which the ACK/NACK is transmitted by the UE ispredetermined to one of a plurality of PUCCH formats by the BS.
 20. TheBS of claim 19, wherein up to 22 information bits are received throughthe predetermined one of the plurality of PUCCH formats.
 21. The BS ofclaim 17, wherein the DCI is transmitted through a physical downlinkcontrol channel (PDCCH) of the downlink subframe.
 22. The BS of claim17, wherein the data unit is a codeword transmitted through a physicaldownlink shared channel (PDSCH) of the downlink subframe or a PDCCHindicating a release of semi-persistent scheduling (SPS) transmitted inthe downlink subframe.